Heater Box Cables stiff

[camgti 56]

Gday all. 
Im deep into cleaning and repairing all the things that dont work smoothly on the Gti and the heater box/blower etc all need attention. 
 

Main issue is the middle fan speed dial that controls the flap is so stiff it breaks the center of the dials (lucky I had a spare). Ive looked at the back of the white dial box where the cables join and the gear/cam device works smoothly. I removed the cable that goes around the back of the box to the flap from the dial box actuator and its fairly stiff to move by hand (pulling and pushing). 
 

Ive taken a very deep breath and removed the whole dash to really try and work out what the issue is. Im convinced that the cable has worn itself a track inside the sheath and it just worn out. I could remove it and spray wd40 or similar down it but I fear it will just be a temporary fix. 
 

Ive not looked into the flap itself but it seems fairly smooth in operation by hand. Anyone had the same issues? 
 

There are new cables available so looking to buy a fresh set and move on if thats the go. 
 

The motor also only works on full and its pretty slow also. This seems like it will just be the resistor which Im hoping to mod with an earth wire and new resistor. 
 

Any advice welcome!