Window lift motor replacement?

[geo]

I do not know how true this is of the Bristol implementation of electric windows (although I did it on mine), but on other cars, reducing the amount of effort on the electrics to raise and lower them makes them work better. In addition to keeping the outside of the window glass clean, mine benefitted from spraying a silicone lubricant on to the guides in the door frame where the edges of the glass contact.

After all, just think of the amount of effort required to lift a window with a non-assisted window winder, it is asking a lot of that relatively small motor.
George