I finally bit the bullet and pulled my windscreen assembly out today. Found the gear in very poor condition. The nylon in the cable was in very poor condition as well. I thought the the nylon is probably the problem in the first place. Expands when warm in an already tight fit tube. My option, take the torch to it and melt the nylon out. Result smoother operating of the cables particularly with new lube in the tube. The screen again moves although the gear teeth favouring the left cable (I think it is the lower section of the gear) are in better condition than the right so it lowers on the left and not the right. Both sides move up with a little assistance. I can at least move my screen again into a new position. End result is that I know my motor and mechanism work fine. I will have to source a replacement gear. There is a bloke who machines alloy parts for race vehicles around the corner. I'll take a gear in and see if a new one could be machined. Should I get a good result from my local guy on the gear, I'll post up the details at the first opportunity.
Sincere regards,
Maxnettoz