Thanks for the reply, but it is not possible to find a suitable replacement VFD. The problem as I understand it is that the spindle (900w max) is a 2 pole 3ph motor with a speed range of 15-60krevs at 15-60volts. I do not need that speed, so would be happy with 24krevs at 230volts and use an off the shelf inverter. I have been advised that whilst I may be able to set the voltage down that low with a 400hz inverter, these inverters are PWM and would still be applying a higher voltage for a short period to achieve the lower working voltage, but that the spindle low voltage windings will not be insulated sufficiently to cope with that. I hope that makes some sense. I certainly had the impression that the "impossible" comment was because there would not be enough space for the revised windings, or indeed that they were not really interested. The spindle body diameter is 62mm, but none of the rewinders I spoke to have seen the spindle, let alone examine it. G.