Something to do when you can't get out there.
After rumaging around in the pantry and the bathroom cupboard I liberated a lid from a near empty 455g jar of Vegemite and the plastic cap off some bathroom product I don't recall now but it was only slightly bigger then the focuser knob.
Center and screw the vegemite lid to the plastic cap, wrap a few lengths of electrical tape around the focuser to make snug fit and wallah! Fine focus control.
