ML7 lathe motor problem

I have just purchased an ML7 with an English Electric one third Horsepower single phase motor on it. The problem is this. When starting there is a spark from within the motor.
This sometimes causes the house RCD to trip. I have inspected the inertia switch within the motor, which is of a good robust construction, but is obviously the location of the spark. Its contacts are in good condition.
Is this a common problem? If so has anyone cured it with RC networks across the switch? Do I have to resort to an external relay operated from the inertia switch?
Regards Bernie
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Bernie Power wrote:

I once had a 120/240 volt motor that was miswired so that the start winding was 120 and the run winding was 240. When it was started on 240, the internal start switch did indeed make a fearful spark. I don't know if your English motors have 120 windings, but if so it might be something to check.
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It could be that the start winding is defective but functional enough to start the motor - as in partially shorted or grounded to the case.
Bob Swinney

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