BMW Repair: 1999 BMW Z3 2.8L Roadster, bmw z3, reference point

Question
QUESTION: I am having a convertible top problem.  It started as the top not retracting if parked on a slant.  Then it progressed to stopping halfway up or down.  Now it is completely not working.  How do I troubleshoot whether it is a problem with the motor, or the top sensor, or the brake sensor, or the switch itself?  Or is it worth disconnecting the motor as I have seen posted in other places?


ANSWER: Do you hear the motor running even though the top is not moving?

---------- FOLLOW-UP ----------

QUESTION: no noise whatsoever...  I did unscrew the T handle on the motor to move by hand, and the fluid looked low in the motor. However, I do not know what "full" is as a reference point.

Answer
with the help of an assistant you need to check power and ground at the motor while pressing the button. If you 12v at the pump replace it. the fluid level will look low but is @1/2 the bottle. you will check it while removed.
         Kimber