Originally Posted by mikeedler
I would guess the motor is bad. I have changed enough of them over the last few years that it wouldn't be very surprising. They aren't as bad as E46 regulators though!
The clicking is normal.
I would try to use 2 jumper wires on the motor direct to a battery and see if the motor turns, if not, you def. know what the problem is.
Thanks mikeedler, you are quite right:
Managed to sort the problem today- had a few hours on it while my lady was preparing for Christmas dinner!
Took the motor off again and measured between pins 5 and 6 (the heavy-guage feeds) with my meter. Almost infinite resistance. Odd I though....it's a motor coil so should only be a few Ohms. So I took the motor out of the other door and sure enough it worked in the faulty door! Tried my old motor directly with a 12V feed and nothing. Result- but BMW Parts had just closed a few mins before!!
So I pulled the motor assembly to pieces (you can remove the commutator from its metal housing and get at the brushes etc.) On very close inspection, it looks like one of the brushes was being held slightly back from its normal position and not making contact. I had a general poke around, cleaned things up with a bit of contact cleaner and re-assembled. When testing with the meter, I now had ~2 Ohms as I would have expected! Connected back up and resinstalled onto the regulator and it's working!!
So fixed (for now at least) for £0 and just a bit of effort!