My Kwikee step (85 Regal-32') has developed the bad habit of only wanting to partially open and close, and because it doesn't go all the way in either direction I have to manually push or pull it the rest of the way or it will just sit there and shiver forever. Before I start tearing it apart I'd like an opinion as to whether it's the motor, gear box or controller.
thanks,
Tigger

Put a voltmeter across the input wires and operate the step.

What is the voltage drop?

Disconnect the step from the arm. Does the motor and gearbox run OK? Does the step move easily by hand?

Run a positive and negative from a battery to the motor connector, reversing polarity. Does the step move in and out OK?

As always, a good, clean ground is important.

A properly lubed and loved step should go out with just a pack of 8 flashlight batteries, and almost go up with the same pack, needing only the slightest fingertip nudging. Crabby and neglected steps require a very well-charged house battery to work right.

First check the electrical connections, including splices. If they're intact (I'd redo them anyway), it's likely the controller.

As bill h mentioned, test the motor disconnected from the controller (IMPORTANT - you can fry the controller if the motor isn't disconnected!)

The bad news is that the 3rd generation controller (you have 1st gen) requires an entire conversion kit to install, and costs almost as much as a new step. Because my step had deteriorated, I bought a whole new step. The step with the controller is only $9 more than the one with just a switch to open and close.

You will probably also have to replace the in-frame magnetic switch, as the old one is NC and the new one is NO.

See this thread.