Slow forward I released the transmission in order to push it to point where it could be jumped to start. After starting, I re-engaged transmission with engine running (contrary to later discovered owners manual warning). Now tractor goes very slowing in forward. Purged per manual, no improvement. What do I do? Did I break something?

its mechanical. belt may be off.

there is a safety shut off switch when blade is engaged. may be stuck on

Bearing noises in a clutch system are easily distinguished by running a few simple tests. Start the engine and leave the transmission in neutral. If a transmission makes noise when it is in neutral it is often a worn input shaft bearing. Now depress the pedal until the clutch just engages. This is the point where the release bearing is just contacting the pressure plate fingers. If you begin to hear a squealing sound this is likely a worn release bearing. If a whirling noise is present when the clutch pedal is fully depressed it is probably the pilot bearing.

check the safety switches start with the one on the pedal

The shift linkage is out of adjustment.

The cable bolt may be loose up at the column, the column itself may be loose enough to allow it to shift position as well.

Make sure column is securely mounted, If not- tighten the 4 bolts that hold it to the dash support so it is. if it is, crawl under driver's side and on the transmission is a bracket where the cable assembly comes into it, and from there a rod that attaches on the lever on the side of the transmission. Make sure the bracket is not damaged or cracked first- if it is, replace it. There is a captive clip to release on the wide part of the piece that the bracket holds, it does not come out fully, but it will release the cable housing so you can slide it to adjust it. With the column shift in Park position, note where the rod is at the transmission. Also make note if the bracket is in line with transmission. If bracket is in line, pull the lever rearward one notch/detent that you will feel engage the lever- this moves the transmission lever to neutral, then with firm pressure push lever forward so you feel 2 distinct notches/detents forward, the lever is now in park. Push locking clip back into position once you confirm the cable outer housing is squarely seated into bracket opening and is soundly clipped into the square opening of the bracket.

If the lever will not move to that second detent or you did not feel it, you will need to check by putting the column shift to first gear position, release the connection to the lever on the transmission just to verify location of lever, and verify the lever is indeed in first gear- the lever on the transmission will move no further- then count detents forward from the rear stop. you should end up in park, and you may hear the parking pawl engage the output shaft of transmission. move lever back to the rear to the stop, reattach the connection to the cable, put column in park, release the clip again and verify the lever is as far forward as it is going to move. Push clip into lock position.

Start Explorer, with foot on brake pedal, release the emergency/parking brake and see if the vehicle moves, or if it is truly in park. It should be in park.

If you encounter some dificulty with getting the column shift lever itself moved over to park- apply brake pedal to release the park interlock mechanism.

You should be able to push it forwards as well as backwards. I had a similar problem (engine stalling) with mine. I found out if I half choke it, it will stay running. Transmission may still have a problem.

The pin disengages a " Dog Clutch " . In order for it to re-engage , the dogs need to be aligned. To do this , release the pin and rock the tractor forward or back till the drive re-engages. Cheers

Yes there is a safety switch.And this safety switch has to be engaged.If its not engaged then the JD tractor will not start. On JD 855 the safty switch is located under the seat, There is a rod that must be depressed before engage Somehow that rod is bent or its not pressing the switch to the point that the seat would not fully engage the safty switch.In some cases the switch itself is faulty.It has to be checked . Thanks. keep updated for any more query.you can rate this solution and show your appreciation.

1) The drive belt between the engine and transmission has broken or jumped off a pulley.
OR
2) Your hydrostatic transmission is dead.

DO NOT STICK YOUR FINGERS UP INSIDE A RUNNING MOWER TO SEE IF THE DRIVE BELT IS MOVING.

auto trans operates on fluid pressure. if the trans has never been serviced, more than likely the filter is plugged, and or the fluid is bad. no doubht its burned and will smell and look like it. get it towed to a shop and have the fliud and filter changed first, then check the band adjustment.recommend a trans shop do it and not jiffylube.