Worn window winder mechanisms - solutions?

[Colin Lindsay]

My convertible passenger door window will not wind down more than 2/3s. It takes a little bit of force to get it to go right down. I stripped the door right down and rebuilt all of the runners, fitted new seals etc but no difference. When I turn the winder to that position the entire centre of the door lifts outwards against the door trim. I reckoned the winder mechanism was worn, so replaced that with a spare - same problem. By dint of an endoscope I was able to see that the entire mechanism is so worn it presses the arms downwards instead of sideways, so they hit off the quarterlight frame and are pushed outwards, rather than moving past it. The movement is amazing, quite a bit of separation between the parts and the entire door frame flexes inwards. Some enterprising PO has also bent the arm, which made no difference at all.

The arms are all held together with large rivets and obviously something is badly worn; too much upwards and downwards movement. Has anyone replaced these, retightened them, used bushes or found any other solution?