Mine went on the Coupe and when replaced they told me it was BMW drive motor but had a "Morgan" attachment on the end which connected the cable up to the lift mech towards the rear of the door. The length of this cable does go around quite a tight bend in the small confines of the door and so as it rotates it puts stress on the join to the custom bracket that fits on the motor so leading to the individual strands shearing off the bracket.
(From memory) As it starts to go you feel/hear a splinter and brushing noise as the strands wipe around then it may work once or twice more slowly with more sounds then it lets go totally and you have no up/down. If it is urgent you can take the door off and manually wind the window up but you need the right tools to avoid damaging the leather. Also once it is up you have to be careful as opening and closing can do some damage to the rubber seal around the inside of the door frame at the top. Leave it just a fraction down so it just brushes it on open/close.
The part is not always easily available I am afraid. I had to wait a while.
Welcome to Aero ownership. Whilst it may pee you off the answer is to drive it MORE not less. The balance offsets the aggravation.
