Hi,
I've read somewhere that regularly when in service (but not while driving) the driver is meant to select each gear in turn and press and release the change pedal a surprising number of times which operates the adjuster for each band/speed selected. If you haven't got a manual then check the NET for 'Doug's Heavy Metal' website as he discusses this with some emphasis (can't always trust my memory). Thanks to Doug's site my Dad got our first Ferret's dizzy timed up and the motor running nicely (Thanks Doug!
).
Regards
Alex