Tap the end of the motor with a hammer - make sure you're well out of the way. Many, many, many old steps stop working due to a dirty commutator. If the motor deploys (or retracts - whichever) when you tap it, you should change the motor.
I used to spend hours testing the fuses, going through the formal testing procedures and then read about tapping the motor. Voila, the motor moved as soon as the mechanical shock made the brushes make contact with the dirty commutator. I went so far as to clean/polish the commutator - and got an additional few months out of the steps so that I could order and replacement motor and do the job at my convenience...
Of course, sometimes it's a blown fuse or corroded fuse holder or bad crimped wire...check your ground also - mine had been a self-tapping screw into a section of painted metal - removed the screw, scraped the paint, and made it right...
2008 Phaeton 36QSH, Safe-t-Plus, Quadra Bigfoot
2017 Jeep Cherokee Trailhawk w/ flat tow wiring mod.
Blue ox, BrakeMaster + BrakeAway, diode lights and charge.