Do your self a favor and don't bother fixing it. Convert to a manual top. I know of almost no e30 cabrios that have power tops that work or have not had work done on them! The motor is just the start, sooner or later you will run into more costly repairs. I'm sure if you ask most mechanics they will tell you that the e30 power tops left much to be desired.
I converted to a manual and it's no problem. Takes 30
seconds to put the top up & down!
Just my 2 cents!