Finally got round to sorting my windows out today.
The passenger side just needed a new rubber, which was a slight fiddle to get down the rear channel, maybe some sort of dry lube like talc or graphite would have helped. Now shimmies up and down like a good'un.
The driver's side has been becoming more and more intermittent the last six months, usually only working if given a thump next to the speaker and even this stopped helping a few months back so, sick of having to open the door to get car park tickets I resolved to fix it today.
The FSM has a very clear testing procedure for the windows and it was pretty quick to diagnose the motor as the culprit so I had to pull it out, this means the regulator has to come out too. A top tip here is that an Oats So Simple pot fits nicely in one of the big holes in the door skin but will do nothing to stop the window dropping in an alarming manner towards your fingers
Once I'd unbolted the window from the jack I took advantage and shoved the new rubber in while the window was out of the way. Motor off the regulator and it will work if I give it a thump on the ground so I stripped the housing off the gearbox and marvelled at all the carbon in there. Cleaned everything up as well as I could and tested again it all whirs away nicely.
All back together and the window works brilliantly. Not fast but I don't think they were from new but I don't need to help it up and the switch makes the window go up and down so I count that a success.
I held off replacing the runs because of the cost (£85 a side with very little discount available) but I have no regrets spending it now.