Quite likely to be the switch, or relay if there is one involved. Especially if the direction switch is the only way to turn it on and off – contacts eventually burn out from sparks which may be why it is the most used – forward – that is not working.

I had one of these years ago.  It came from Chester Hobby Store.  They used to hold spares, don’t know if they still do.

Russell

I would think it is most likely the reversing switch.  Too many change direction while the motor is still operating.  The contacts are often not rated as a switching contacts and can get burned.

I avoided switching direction, on my old lathe, while the motor was powered.

switch. if it was the motor it would not run ether way. could test by disconnecting the motor from the lathe and fitting a feed directly to the motor.

I would suspect the reversing switch, maybe used without stopping the lathe first before changing direction.