The Lotus Grand Tourers

After my problems with a failed window mech. at the weekend, I've managed to find enough bits in my "big box of things I'll never need" to build up a working motor, but it's still a bit sluggish towards the middle of the travel.

Now, I have a theory about this - obviously window frame alignment can have an effect, as can rust bubbles pressing on the felt channel - BUT : there's a coiled spring attached to the regulator. I think it's there to stabilise the system (to prevent it flapping up and down too easily) and to give a little boost in the form of mechanical force, but it corrodes and that means that the coils don't slide smoothly over each other as well as possibly weakening the spring. Is it possible that those of us with slow windows are suffering from the effects of corrosion here ?

All thoughts and experiences welcomed.

The spring is there to overcome the effect of gravity on the glass and operating arm. You would need a much bigger motor without it. Springs do lose tension over time, so the help offered by the spring would reduce making the motor work harder to lift the window - slower. You are right about the friction caused by any corrosion. It may be possible to move the spring attachment point on the arm to compensate.

Pete