Today I fixed my driver's side window (I've had issues before so I'm pretty slick at this now). I've just been waiting for a long enough break in the rain to take it on.
The cure was - same as last time - cleaning brown rust out of the connector block on the door window control ECU. I'm reporting this again because now I'm absolutely certain that this will be the cure for many people's window issues with GTs. I suspect that many hundreds of pounds worth of regulators, ECUs and labour hours have been thrown at this over the years when a little scrape and a scrub could have done the trick.
My fault symptoms were pretty standard from what I see others post. First off the one-touch function failed. Then the closing or opening of the window took increasing numbers of presses to complete. Then it stopped working altogether only to seemingly fix it self some time later. I could be stuck being unable to open or sometimes to close the window. Then even though the window couldn't be operated the "drop on opening the door" would continue but dropping further than normal - of course it would then not go back up when closing the door. Eventually it failed completely, mercifully I eventually got the glass into the fully closed position. This of course results in the tuneful experience of the wind whistling through the trapped rubber seal; wonderful (but at least the weather mostly stays outside).
As referred to above I was pretty confident I'd be able to fix it at zero cost like before.
The ECU I refer to is inside the door card a rectangular black box about 5 inches by 3 inches, behind and just below where the door switch mounts. Two multi pin connectors are attached - one black on the left and a slightly larger white one on the right. It is the white one where, twice now, I've had the trouble. A couple of things have probably worsened my situation; the waterproof membrane is mostly missing on that door; and recently I somehow managed to fully open both windows with the remote accidentally and leave them open all night - we had heavy rain the entire night -oops!
The fix is simplicity itself, having removed the door card (search elsewhere for details) I removed both plugs from the ECU and looked for discolouration. Exactly as before I found signs of rust on the right hand side of the white block. The connectors on that block are partitioned up into segments the right hand end partition comprising places for two rows of three pins top and bottom - on mine only the bottom three are populated. The leftmost one of them, on mine, has become blackened and the corresponding socket in the plug carries a permanent 12v supply, even with ignition off. (You may wish to disconnect your battery because of this - I didn't bother and no harm was done but take care not to short it out). The next connection, the one to the right of that - the middle one of the three, is where the trouble occurs (I expect this to be the route back to Earth because so often with car electrics it is a bad Earth that is the issue). Using my tiniest flat blade instrument screwdriver I scraped the surfaces of both the relevant pin and socket to remove surface contaminants then a good spray with contact cleaner and a scrub with a stiff plastic bristle brush (I've got one mounted on the contact spray can I use - but an old tooth brush would be good too) don't use metal bristles if you haven't disconnected the battery because if you do you'll get your own little fireworks display. You can reconnect all the plugs and the door switch before reinstalling the door card, for testing, to make sure all is well (but they need to come apart again for final assembly). Hopefully you will find that Robert is indeed your aunty's husband. But even if it isn't it's better to rule this out BEFORE buying expensive replacement parts (like I did originally