Thanks for the responses guys. Naturally, as I made the plate, I double and triple and quadruple checked the screw lengths, they're plenty out of the way, but I just tried it off the mount and it behaves the same.

The motor and ESC are both sensorless.

Reviews on HK are very positive for this motor, so I may do best to try and get another one, but naturally I'm put off. There aren't many alternatives in my price range, sadly. The Align is usable but I think the poor thing will give up before long, it's had a hard life. :P

Not sure what to do!