Hi Again Mark

Just realised that you said the motor just buzzes in either direction, which I assume means you have a Dewhurst type or similar reversing switch fitted to the machine. These reverse the connection to the start winding to change the direction of rotation, if the contacts on these are excessively burnt or pitted, which can happen, it could also affect the connection to the start winding and cause your problem. Still worth carrying out the above tests, but it does complicate the electrical fault finding somewhat. Depends if you have and are comfortable with using a multimeter.

Dave

This type of fault has been covered many times, several occaisons recently, Look in the archive for motor issues. Since you mention a direction switch it could be a Santon or the Dewhurst and the contacts could have failed. Strip the switch and inspect the contacts, which will almost certainly show signs of burning, it may be posible to clean them. THEN rewire with an ON/OFF switch BEFORE the reverser, select direction then turn on ! As Roy has said they should NEVER be used to stop or start the motor ! The motor may not yet be spoilt but DO NOT leave it buzzing for long or it will be ! If you are not OK with working with electrics then you will need help. Could be the start capacitor has failed, quite common on old equipment. Not to expensive and would need to be replaced. NOTE VOLTAGE and it must be a motor start capacitor ! Could be the centrifugal switch. If you take the belt off, spin the motor by hand and turn on it MAY spin up to running speed ! Turn off and listen for a CLICK as it slows, this is the switch operating, though the contacts may be burnt, they can be cleaned but this requires the motor to be stripped. A wiring fault may have developed – find and fix, or it could be that the start windings have gone – terminal ! Noel.

Not all single phase motors have start capacitors, the one on my ML7 didn't.