The knob is replaceable by yourself, it just pulls off and a new one pushes on. Reasons for free wheeling are :- the sleeve of the knob being split where it grips the shaft, or the small spring steel insert in the end of the sleeve fallen out (if knob falls off easily look in hole in facia for a small square clip if so refit it in end of knob sleeve and you wont need to replace knob ), If not these probs there is also a very small coupler further in the mechanism which can break but you would need engineer to replace that one .Cheers
Kenjo, May 2012
