I had this on my Garmin Oregon, the rubber had perished on my well used one. I nabbed my wife's seldom used Oregon of about the same age, well over 10 years, but the rubber had perished on that too.
The switch on this model, I don't know about others, is contained by a plastic cylinder, and operated by the rubber cover which has a projection on it to touch the switch.
After some faffing around, I whittled a bit of wood to fit loosely inside the cylinder on top of the switch, and covered that with some plastic tape. Works very well.
The tape will have a short life but is trivial to change.
A good result.