New window motor in (nearly killed me getting that in), for any future people who read this the trick not mentioned in the instructions is to a) remove the door handle bracket and b) dismantle the motor from its plate by taking out the three bolts.... then it all fits better.

and to answer my original question (because I hate unresolved threads), if the motor fails in a down position you can remove the window from the motor bracket (two 10mm nuts), shove it back up into place and jam it up with something.

I wish the previous owner had done that rather then let rain into it for years.