KitchenAid KFPM770 motor runs 3 seconds and stops

Check that the safety lock pin is releasing from the base. It is the thing in the tube down the side of the bowl that the lug on the lid engages with. It stops the motor running with the lid off..

https://www.google.com/search?q=Kitchen+Aid+food+processor+bowl+stuck

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There will be a switch activated by correct engagement of the bowl, lid and pusher. Locate and activate that switch without the bowl on and see how it runs then. If it does then you need to figure out which of the bowl parts is not operating the switch properly. If activating that switch changes nothing then then you will need to be looking inside the motor housing, so far it's a place I haven't been on that model.

Most often when that model processor stops working it is associated with the mechanisms in the lid and bowl that activate the safety switch that prevents you turning it on when the bowl & lid is not on correctly. The mechanisms are not repairable, the fix is to replace the bowl or the lid or both. A proper KitchenAid service agent should have both in stock, take your complete machine in so that the faulty part can be identified.

Probably the mechanisms in either the bowl or the parts of the lid that engage the bowl mechanisms.

Does the actuator push down far enough to catch the button at the bottom? I repaired one simply by adding a vinyl screw cover to the top of the button so it was tall enough to be reached by the actuator.

Most likely it will be to do with the bowl or the lid. The safety mechanisms in both parts are likely culprits, they operate a micro switch just above the switch panel and hidden by the base of the bowl. Have just the bare motor plugged in and turned on with the run button depressed. Now with something plastic depress that small black button, the motor will likely start running. That proves motor is fine and you need to figure out which of the bowl or lid is the faulty part. The pusher needs to be in the lid tube before the motor will run in case you have forgotten.

I am assuming the unit is getting power. The "power" LED should be lit up on the front of the unit.

The Kitchenaid food processors have a few safety features implimented. If the unit is not assembled properly, this may prevent the unit from turning on. Proper assembly is below:

If it isn't all ready, please disassemble the entire unit. This means removing the blade and/or disc, blade, removing work bowl, work bowl lid, and blade.

Start by placing the work bowl onto the motor base. The work bowl handle should be facing at 9 o'clock, which is out to your left. Rotate the handle downward until it locks in at the 6 o'clock position, which will lock over the center of the button panel.

Repeat the process with the work bowl lid. The blade does not need to be present for the motor to engage, if this is an assembly issue.

If this has not resolve the issue, please ensure the outlet is receiving power.

If the unit is still not functioning, take a close look at the bottom of the work bowl where it meets to the motor base. The work bowl, when locked in, depressed a gray plastic peg. This is the safety mechanism. You may trying depressing this peg on your own with a pencil. If this activates the motor, this may indicate your work bowl is no longer seating correctly.

Also check the work bowl handle to make sure nothing is cracked. There is a plastic assembly in the handle that acts as a second safety feature.

If either of these things seems to be the culprit, I would suggest seeking a new work bowl or work bowl lid to correct the issue.

The Kitchenaid food choppers have a few safety features implimented. If the unit is not assembled properly, this may prevent the unit from turning on. Proper assembly is below:

If it isn't all ready, please disassemble the entire unit. This means removing work bowl, work bowl lid, and blade.

Start by placing the work bowl onto the motor base. The work bowl handle should be facing at 9 o'clock, which is out to your left. Rotate the handle downward until it locks in at the 6 o'clock position, which will lock over the center of the button panel.

Repeat the process with the work bowl lid. The blade does not need to be present for the motor to engage, if this is an assembly issue.

KFC3100 Manual is posted at http://www.kitchenaid.com/assets/pdfs/product/ZUSECARE/9705624.pdf

The clicking noise is an internal circuit breaker or motor protector. These things are not made to be bogged down or overfed. The motor is heating up & tripping the overload, after cooloing it resets. Time to buy a new one or get the motor replaced ($600-$800)