I just bought it used and when I turn it on and the put the safety key in it beeps but then the speed display blinks different speed, I can hold down whatever speed that I want on the display and then hit the quick response and it will stay at the speed selected but the speed display continues to blink different speeds and beeps the whole time, Ive taken it apart and cleaned out any dust but it does the same. Any idea if it is the board or the motor?
thanks

Eddie, December 2014