If you check your phone book (larger cities) you should be able to find an industrial sewing machine repairman. They'll have you take in the head (unless there is a problem with the motor). I bought an industrial on ebay, and it was nearly frozen. The serviceman was able to wash it in kerosene to get it working again.
As a side note, I understand there are two kinds of motors, clutch and servo. The clutch motor runs all the time, and by pressing the foot pedal, you engage a clutch that runs the sewing machine.
The servo motor only runs when you press the foot pedal, and only as fast as you press the pedal.
I keep hoping my clutch motor will die so that I have an excuse to by a newer servo. The noise drives me nuts!!