As it had got to the point that I needed two hands to get the window back up it was time to fit a new window window return spring. What follows is how I managed it. It is important that when you access an area that is normally hidden you check everything out while you have access.
First remove the door card, note that I have added a sheet of waterproof paper, to keep rain off the door card.
This is the general layout of the winder mechanism. The spring has been released from the anchor.
Before removing the winding mechanism, prop up the window.
As usual there is a mix of screws holding the mechanism to the door frame.so a box is used to show what belongs where..
Having removed the old spring, with this wire puller, the new spring can be pulled into position while held in a vice. A firm fixture is important as the spring takes quite a strong pull to engage the hook in the anchor. I obtain copper wire from mains cable.
Care is needed to avoid a flying spring!
On the nearside door some problems, the tabs securing the window winder gear were loose and needed tightening up. The grease on the slider was set like tar, very hard and sticky. Also the sound deadening material had become detached and needed heating up and re-securing to the door panel.