Is been installed in his workshop for at least 40 years on a dedicated 3 phase supply with no problems, so unless anything has changed to that, I have to assume at this stage it’s still ok.Is he running on proper 3 phase or through a vfd?
If I've followed this correctly: the high/low speed range switch has been changed and now it only runs at one rate irrespective of the switch setting. Was the replacement switch correct and was it wired in correctly.??
Seems unlikely the motor (4 pole/12 pole) has a fault where it runs at the same rate on both sets of windings.
Slightly off topic but the motor is UK made. Were Hardinges made over too?