Just noticed a significant error in my drawing - the bore through the red bit is a constant diameter, so the bearings would come out from either end if it wasn't for the adhesive. I could try warming up the stator/bearings together to loosen the glue... I don't want to break anything though as this was quite expensive! If the right glue is used then this shouldn't work, I think, because otherwise they'd come loose during normal operation.

I wonder if heating the motor and freezing the collet chuck might make enough clearance to assemble it?