Hi, I have a Pro 600 mixer that I just rebuilt with new gears. The unit also needed a new planetary as the shaft became loose causing some metal shavings in the housing.

When I returned unit to operation the motor began hesitating. I at first thought the shaft was dirty where the electronics found a "dead spot" on the contact. The unit doesn't respond to any movement on the speed switch. I found that I could start the motor by moving the fan though this would be impractical once the unit housing was replaced. I can tap the back of the housing to get the motor started. We also find the motor seems to run slower than the other units we use. I don't know if this would be the motor, the brushes (if they are replaceable) or the electronics.