Hi Jazz,
OK, thanks for that. I can make the fan quieter with a bit of acoustic treatment.

Clive,
Thanks for the info. Start/stop and pot has worked well for many years on the old VFD so will most likely go with that option.

Jonathan,
Yes, first thought that crossed my mind was that they owe me about £15 or so! I'll email them and see what they say.

I've settled on getting this one to work - if I go down the route of sending it back an insisting on the 2.2kW unit, and it is faulty (or develops a fault), it could be a difficult discussion.

This afternoon I managed to connect up the spindle and when I pressed run it smoothly ramped up to 24000rpm. It ran in the wrong direction, but easy to fix that one. Another step closer . . .