A bit like the foil method but I cut to size a strip of the reflective insert taken from the packaging for a pair of Osram H7 Night Breaker bulbs. [I'd heard of the foil trick but as we were out for a drive at the time of need I utilized what was to hand in the boot.]
I did think I might eventually have to resort to Loctite 243, a medium strength threadlocker, but the gear knob stayed put for the remainder of our ownership which must have been a further two years. I can only suggest this may have been down to the reflective insert being thicker than foil.
