DDK - Die Deutschen Klassiker

I've been told that the electric windows on the early 911s are normally useless.Mine are. Any alternative motors that can be used?Help/advice appreciated.

Its usually the channel felts that cause the problem

Used mine for 2 years daily driving on the black car
Never had a major problem
The drivers one would get stiff going down every so often (Maybe I should rephrase that )
It would open 5 inches then slow and stop
As Nick says it was because of the felt so an assist with the hand to wiggle it and it would go down the rest of the way
It was always faultless closing it and the lh never ever had a problem.

In fact most people sitting in the car asked if they were a later add-on

Mine do and always have worked perfectly in fact if anything they are a little too quick.

I suspect that, as Nick suggested, they need fettling more than anything else.

Mine are slow and the drivers side needs a little help on occasions, but they work.

My drivers side (manual) packed up last year - got it fixed but still a little stiff......couple of squirts of silicone spray in the runners did the trick!

I think the early sunroof motor is the same or similar. replacements are rare these days...