Hugh, For my TA21 I fitted the knobs on to a wooden shaft and then placed the other end into the variable speed electric drill. The drill was then placed into a bench vice. All in all the knobs spun round at a safe speed and I used an automotive cut and polish that came in a tube. I found that the rotating knobs cleaned up very well and had a nicer and more uniform finish. I did try buying reproduction parts but the colour was not quite the same and it did not match well with the same colour radio controls. Hope this helps. Richard Melbourne Posted by RichardWallach 22/09/2014 11:11:29