Welcome to iRV2.
From your description , it sound like you have a broken tooth in the drive gear system , Because the gears go forward then reverse they always stop with load on the same tooth , so damage to that one tooth can cause your problem.
The gear drive system is not complicated , the biggest problem will be getting the gear box apart because of rust and corrosion from being under the coach for many years on the road.
Kwikee steps , originally produced by Power Gear has been recently bought up by Lippert.
If you don't have the users/parts manual for your steps then going to this site will get you the free download as a pdf .