Remove the wall plug and allow 10 minutes for the motor to cool. Then, check the drive chain or drive belt and look for broken gears and worn ram screws. To find the switches on your unit, check the owner's manual. Then test each switch. Check every wire and connection.
Unit starts, but blows a fuse of trips the circuit breaker.
Short circuit in cord or plug. Short circuit in switch. Short circuit in motor. Test the plug and cord for continuity. Test the switches for continuity.