Red DiddyBorg v2 - problem with single motor

Hi,

I'm coming to the end of building a Red DiddyBorg2 and am having a problem with a single motor. All the motors are connected and most of them are running fine. However one refuses to move. A multimeter suggests there is a voltage across it and very very occasionally it will move a tiny bit when power is applied, however on the whole it just does not move (it does get hot though - much hotter than the working motors).

- I've tried removing the wheel and the hub from the motor to check there is no external obstruction and the same problem occurs
- It is not wiring either - I removed all other motors from the ThunderBorg and left only the problem motor in place - same issue
- I've tried the suggestions under https://www.piborg.org/blog/thunderborg-troubleshooting under Use Issues. GetDriveFault1 and GetDriveFault2 both return False (all the motors run during the test bar the problem motor which again gets warm etc). GetEpo does not appear to be defined for the ThunderBorg, so that is no use.

It appears that this motor is faulty. Is there anything else I can do to test? If not how do I return the motor for replacement for a working version? (the advice on ModMyPi just points to these forums).

Thanks