I'm a great fan of the drill technique too Dave. I try and use a 6mm tapped hole (5mm drill for 6mm tap) then use an adapted 6mm bolt and a lock nut.
I then mount it in the drill press to carry out the adjustment.
Stihl power tools suffer a similar issue on their pull starters. the spindle is a hard plastic of some sort and it swells and jams preventing the pull cord from retracting so I've done a few of those in my time as well although the same level of accuracy isn't required there!
