Quoted from RestonVA:I don't think there is a specific test for them, but I did try burn in mode, and they don't move during burn in.
There's a motor test for the death star, I think it's under the coil section. You can step through each in the diagnostics. More than likely the motor's gears are all stripped out or the motor's dead. Since you've seen both work occasionally, this seems most likely. If they were totally dead, I'd say check the transistor Q24 which controls the death star motor.
Could also be an intermittently working relay.