Well this wasn’t as bad a job as I was expecting. 👍
The issue started to become apparent a few weeks before total failure, with the drivers window switch intermittently failing. Over the next two weeks the failure progressively became more frequent, finally giving up the ghosts entirely.
Diagnosing the problem started with me testing the others window switches with both front and rear near side working but neither front nor rear offside working.
The other issues that came up were that the off side doors wouldn’t lock (however the fuel cap did), the mirror adjusting switch also didn’t work and there were no lights to any of the drivers door switches.
After a bit of Googling I found myself inspecting the door harness between the hinges. After peeling the rubber sleeving back I could see that a number of the cables had broken.
I ordered a repair kit from eBay and got to work when it arrived. https://www.ebay.co.uk/itm/Left-Right-Door-Cable-Wiring-Harness-Loom-Plug-For-SKODA-ROOMSTER-SUPERB-YETI/333814539014?hash=item4db8e5a306:g:RVkAAOSwnRpfyz47
I decided to replace as much of the harness as the kit provided as, in my opinion, trying to fix the issue in the hinge would only lead to failure again as the existing cable was very brittle compared to the new stuff in the repair kit.
I cut what remained attached to the harness connector, removed the door card and pulled the harness through the door.
I trimmed the cables back to the outer skin of the door and used these brilliant soldering joints to attach the new tails on. (My soldering has never been as good as I would like and these things are so easy to use.)
https://www.ebay.co.uk/itm/281x-Waterproof-Solder-Seal-Heat-Shrink-Wire-Cable-Connectors-Crimps-Butt-Joint/393138233400?hash=item5b88dd6038:g:dmkAAOSwdPxgLf-Y
After extending the harness, re-taping and pushing back through the door and protective hinge cover and that remained was to hook up to the new connection block.
Abracadabra, everything was working again. The job took around two hours to complete and is easily done with a few basic tools.
TIP
To remove the rubber sleeve between the door. Pull the harness cables through the door, then push the sleeve into to door and then pull it out. I think trying to pry it out will lead to damaging the sleeve.