I usually find diagnosis of a problem harder than the fix. My 1988 RRC electric windows seemed to have got really slow. Over the years I have tried: 1. Cleaning and lubricating the channels 2. Powering the lift motor directly from the battery 3. Lubricating every moving part 4. Straightening the window frame so that its curve more closely matches the glass 5. Swapping motors around. This weekend it occurred to me that the windows go down much faster than they go up. Diagnosis: the counter weight spring is tired. The fix: remove motor and remove the arm mechanism from the car, release the spring and reposition it so that it is much tighter and gives the window more lift. While I had the mechanism in the bench vice and after tightening it, I put a fishing scale on the end of one of the arms and recorded 3kg pull. This was almost right to balance the front window when it is in the car with mechanism in place, but without motor. After refitting the motor, the window speed down is slower than before, but the speed up is definitely faster. I am so pleased with myself for coming up with this simple, no cost, fix and embarrassed that it has taken over 24 months to think of it! I hope it helps someone else.