Had to get back to the sucker.
Lately (in May), the power window missed the last inch up. Only with "helping" hand the window'll go all up (driver side).
First things first - test the power window switch - it's allright, does what it should. Good.
Applying power directly to the motor - only works, if you kindly hammer on the motor or if you push/pull the window by hand. So, it is likely that its an issue with the contacts inside the motor. Phew...
Again, door apart, motor removed. Wow, it's an "American Bosch" with date code "8 10 78"

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Pulled that motor apart - aside of some rusty rubbish on one contact and of course lots of remains of the contacts, looked good. But one of the two contacts was not really up to the job "push to rotor for contact".
Getting the rotor off to see that one of the springs behind the contacts was rusted away halfway... Oh my...
But easy solution: take the spring of an oldschool ballpen, cut in half - and there you have your two new springs for the contacts.
Cleaned it all up a little, put it back together, don't forget to put a good drop of grease in the the lower "bearing" [which is no bearing, but better have it greased], add some more grease to the old gaskets (if you have no new) because the motor is on the water side of the door), and the motor runs again as new.
A little bit too fast too clean - remains of the original "American Bosch" "8 10 78"
Mostly cleaned already. Down in the dark hole in the middle a little grease goes.
Good to see the protection unit.
The longer spring was fine and ok. The shorter spring was the remains of the other one. Disintegrated to nasty rusty rubbish inside. So, no good contact possible anymore.
Rotor with contacts, also mostly cleaned already. But what should go wrong with this sturdy motor rotor.
Original spring below, half ballpen-spring above. I put it in that the upper end of the ballpen-spring is pointing to the contact. This way I avoid the sharp tip (cut) to work its way into the contact...
Back together. Easy to work on if everything is open. Whoever has reman'd a starter motor knows, that you'll need a special tool to get rotor and contacts back together (did that years ago with my Charger's starter). Here, no special tools necessary (aside the usual patience and a small screwdriver).