Greg,
Check to see what voltage is at the 2 studs on the control arm near the motor when extending and trying to retract the awning. Since the voltage/gnd is reversed to retract the motor, it would seem that the wiring from the control box to the motor is OK.If you are getting a low voltage, check for a poor ground. I had a similar problem and ended up using the ground from the co-pilot chair rather than the ground as wired to the control box. (also could be a poor 12v connection).
Steve