Chas

If the whole unit will not power up or just trips straight away, you have no bare wires then suspect the transformer itself. If it is only part of the lathe that does not work then it would be the contactor for that circuit (normally just the energising coil). There is not a lot that can really go wrong, i'm wiring a new lathe up from scratch at the moment myself. What does each contactor feed? tell us more about the controls? is the contactors controlling motor, pump, light etc?