I haven't worked on one before but think    it would need to be level. There are quite a few steps to getting the playfield clean/low friction. I think you need to clean, wax, then use shuffle alley powder and the rubber at the back needs to be fairly good condition to get the rebound.

On the motor problem, is there only one switch on the cam? A lot of EM games, have one switch to keep the motor going after initially being triggered and a second switch to turn the motor off at the end of the cycle.