I have a 790r and the detent pin on the lower

Here's Janome LO error;

LO: Replace the foot controller.

1. Check for a tight or stuck clutch by the hand wheel.
2. The machine may be jammed. Remove the timing belt to locate whether the bind is on the upper shaft or lower shaft. If it is the upper shaft, there may be thread caught in the take-up lever or crank pin. If the lower shaft is binding, check hook clearance, hook backlash. Check the lower shaft rear bushing for any black 'gunk'. If there is, replace the lower shaft and rear bushing.
3. Clean the sensor on the DC motor and check if the shield plate on the motor is not loose or hitting the sensor. If either the sensor or shield plate is damaged, replace the motor.
4. Check the upper shaft sensor. Make sure the shield plate is going perfectly thru the middle of the sensor. Replace the sensor and/or shield plate if damaged.
5. If you still get the error, replace the DC Motor or upper shaft sensor (in this order).

My first thought is if you're running nearly non-stop for an hour the motor is overheating. Not sure what the maintenance schedule is for this machine <?>. May need a good cleaning/lube. Then foot pedal, then other.

Check with hand wheel some of the block mechanical. And check cam setting.

check first with a service dealer as the shafts would be difficult to break and there probably is a shear pin in the drive to prevent shaft and auger damage
if that is the case you can drive out the broken bit and tap in a new pin( available from the service dealer

On reviewing the manual, there are two cautions regarding installing the shift shaft that may be the source of your problem. One, the shaft must be installed with the detents at the front end of the shaft facing upwards. These detents are what the ball/spring seat into when the shaft moves forward/aft (like into 1st/2nd gear). The shaft can be installed 180 degrees out, but you would not feel the shifter 'lock' into gear.
The second caution seems more probable. When inserting the roll pin holding the shift shaft lever and bushing onto the shift shaft, the roll pin must be driven down flush with the surface of the shift shaft lever. If not driven flush, it can bind on or interfere with the movement of the bushing, possibly preventing the lever from being able to engage all of the three shift forks (3/4, 1/2, 5/rev). There are two roll pins used with the shift shaft. The shorter one (7/8") is used to secure the shift shaft lever/bushing and the longer one (1 1/4") to secure the shift socket in the rear.
Unfortunately, confirmation will require removal and partial disassembly (removal of the front case) to confirm.

If bolt broke in crank shaft - you'll need to get some professional help to get it removed. The PTO slides down off the shaft - but you'll probably need a wheel puller to get it off. I had to clamp the upper and lower halves of the PTO together to pull them off as a unit.

Adjustment

1. Place parking brake lever in -full released- position.
2. Raise and support vehicle.
3. Remove plug in parking brake shoe support to access adjuster star-wheel.
4. Through the access hole, rotate the adjuster star wheel in the following direction to expand the shoes outward against the drum:
   1. Left brake - Rotate star-wheel toward rear of vehicle.
   2. Right brake - Rotate star-wheel toward front of vehicle.
5. Using an appropriate tool, turn adjuster star wheel until wheel will not rotate (dead lock).
6. Back off adjuster six detents (teeth).
7. Rotate wheel, checking for light drag. If drag is too heavy, continue to back off adjuster one detent at a time until light drag is present. Do not back off star-wheel more than 17 detents from wheel lock.
8. Install access plug.
9. Adjust opposite wheel parking brake shoes using same method.
10. Lower vehicle.
11. Apply and release parking brake lever once to ensure proper operation of parking brakes.

Removal & Installation NOTE The following procedure may be used to remove shoes on either side of the vehicle.

1. Lock out automatic adjuster in parking brake lever.
2. Raise and support vehicle.
3. Access and remove rear hub and bearing.
4. Remove parking brake cable bolt at knuckle.
5. Completely back off parking brake shoe adjustment.
6. Remove parking brake shoe adjuster spring.
7. Remove shoe adjuster.
8. Remove upper brake shoe hold-down clip and pin.
9. Remove lower brake shoe hold-down clip and pin.
10. Remove upper and lower shoes with return spring from shoe actuator.
11. Remove return spring from shoes.
    
    

    Fig. View of the actuator (1), support (2), adjuster spring (3), return spring (4), caliper adapter (5), shoes (6), hold-down clips and pins (7) and adjuster (8)
    

To install:

1. Install return spring between upper and lower shoes.
   NOTE Before installing shoes on actuator, make sure actuator hooked to rear cable is positioned with word -UP- facing outward.
2. Install upper and lower shoes with return spring on shoe actuator located on parking brake cable.
3. Install lower brake shoe hold-down pin through rear of support and lower shoe, then install hold-down clip.
4. Install upper brake shoe hold-down pin through rear of support and upper shoe, then install hold-down clip.
5. Install shoe adjuster. Place end of adjuster with star wheel upward.
6. Install parking brake shoe adjuster spring.
7. Install bolt securing parking brake cable to knuckle and tighten bolt to 21 ft. lbs. (28 Nm).
8. Using Brake Shoe Gauge, Special Tool C-3919, or equivalent, measure inside diameter of parking brake drum portion of rotor.
9. Place Gauge over parking brake shoes at widest point.
10. Using adjuster star wheel, adjust parking brake shoes until linings on both park brake shoes just touch jaws on gauge. This will give a good preliminary adjustment of parking brake shoes, before a final adjustment is made at end of this procedure.
11. Install hub and bearing with wheel speed sensor as well as all components necessary to access it.
12. Lower vehicle.
13. Unlock automatic adjuster in parking brake lever.
14. Perform final adjustment of parking brake shoes

15. 
    Adjustment This vehicle is equipped with permanently sealed rear wheel bearings. There is no periodic lubrication or maintenance recommended for these units.
    

    
    Removal & Installation

    1. Raise and support vehicle.
    2. Remove wheel mounting nuts, then tire and wheel assembly.
    3. If equipped with AWD:
       1. Remove cotter pin, nut lock and spring washer from half shaft.
       2. While a helper applies brakes to keep hub from turning, remove hub nut and washer.
    4. Remove brake caliper and rotor from hub and bearing assembly.
       
       

       Fig. Hub assembly
       

    5. Disconnect vehicle wiring harness connector at wheel speed sensor connector.
    6. Unclip wheel speed sensor connector from spare tire mounting support.
    7. Disconnect two sensor cable routing clips on rear suspension crossmember.
    8. Disconnect two sensor cable routing clips along toe link.
    9. Disconnect sensor cable from bracket on brake support.
       
       
    10. Completely loosen, but do not remove four bolts fastening hub and bearing in place. Once loosened from threads in hub and bearing, push bolts up against rear of hub and bearing to keep brake support plate in place when hub and bearing is removed.
        
        

        Fig. Rear hub and bearing mounting bolts
        

    11. Pull hub and bearing off knuckle and half shaft (if equipped with AWD), then thread wheel speed sensor cable through hole in brake support plate as it is removed with hub and bearing.
        
        
    To install:
    
    1. Position hub and bearing bolts though rear of knuckle and parking brake support just enough to hold support in place as hub and bearing is installed.
    2. Install hub and bearing by first feeding end of wheel speed sensor cable through hole in bottom of parking brake support. As this is being done, if equipped with AWD, slide hub and bearing onto half shaft. Place hub and bearing through brake support, onto knuckle, lining up mounting bolt holes with bolts and placing wheel speed sensor head at bottom.
    3. Install four bolts fastening hub and bearing in place. Tighten mounting bolts to 60 ft. lbs. (81 Nm).
    4. Place wheel speed sensor cable routing grommet into bracket on parking brake support.
    5. Route wheel speed sensor cable along toe link and rear suspension crossmember connecting routing clips where shown.
    1. Connect vehicle wiring harness to wheel speed sensor connector.
    2. Install brake rotor and caliper.
    3. If equipped with AWD:
       1. Install washer and hub nut on end of half shaft.
       2. While a helper applies brakes to keep hub from turning, tighten hub nut to 180 ft. lbs. (244 Nm).
       3. Install spring washer, nut lock and cotter pin on end of half shaft.
    4. Install tire and wheel assembly. Install and tighten wheel mounting nuts to 100 ft. lbs. (135 Nm).
    
    
    

    
    
    

General Description
The front suspension allows each wheel to compensate for changes in the road surface without affecting the opposite wheel. Each wheel independently connects to the frame with a steering knuckle, ball joint assemblies, and upper and lower control arms.
The control arms specifically allow the steering knuckles to move in a three-dimensional arc. Two tie rods connect to steering arms on the knuckles and an intermediate rod. These operate the front wheels.
The two-wheel drive vehicles have coil chassis springs. These springs are mounted between the spring housings on the frame and the lower control arms. Double, direct acting shock absorbers are inside the coil springs. The coil springs attach to the lower control arms and offer ride control.
The upper part of each shock absorber extends through the upper control arm frame bracket. This bracket has two grommets, two grommet retainers, and a nut.
A spring stabilizer shaft controls the side roll of the front suspension. This shaft is mounted in rubber bushings that are held by brackets to the frame side rails. The ends of the stabilizer shaft connect to the lower control arms with link bolts. Rubber grommets isolate these link bolts. Rubber bushings attach the upper control arm to a cross shaft. Frame brackets bolt the cross shaft.
A ball joint assembly is riveted to the outer end of the upper control arm. A rubber spring in the control arm assures that the ball seats properly in the socket. A castellated nut and a cotter pin join the steering knuckle to the upper ball joint.
The inner ends of the lower control arm have pressed-in bushings. The bolts pass through the bushings and join the arm to the frame. The lower ball joint assembly is a press fit in the lower control arm and attaches to the steering knuckle with a castellated nut and a cotter pin.
Ball socket assemblies have rubber grease seals. These seals prevent entry of moisture and dirt and damage to the bearing surfaces.
Four-wheel drive models have a front suspension that consists of the control arms, a stabilizer bar, a shock absorber, and right and left torsion bars. The torsion bars replace the conventional coil springs. The lower control arm attaches to the front end of the torsion bar. The rear end of the torsion bar mounts on an adjustable arm at the crossmember. This arm adjustment controls the vehicle trim height.
Two-wheel drive vehicles have tapered roller sheel bearings. These bearings are adjustible and need lubrication.
Four-wheel drive models and RWD Utilities have sealed front-wheel bearings. These bearings are pre-adjusted and need no lubrication.
Heat treatment may create darkened areas on the bearing assembly. This discoloration does not signal a need for replacement.
Hope this helps?

Double check the wiring to the ignition unit and make sure everything is still lined up correctly.

i had the same problem. had a knocking on the engine and let the vehicle sit until i had time to look for the problem. my unknowing mom took the car without permission and the car broke down on her. as it would turn out the upper timing guide rail broke off and damaged the cam gears and broke the upper timing chain along with damaging both the right and left lower chain guides, and the tensioner was also damaged. i would recommend that u inspect the lower chain to make sure that everything is good.

If the machine stops abruptly with a clatter, make sure you don't have a loose looper that may be allowing the upper and lower to cross when they meet. You do not want to break on of them.
If it runs for a few minutes and starts to drag down slowly until it stops, the problem is probably with the upper shaft. Many technicians don't lube the upper shaft because it is harder to get to than the lower. Check upper shaft bushings and the link pin to the needle bar. Bushings need a clean and lube, link pin will probably require replacement if it is causing problems.