Hey my switch had started to stick a little bit. Nothing major, just a feeling thing: it made a little "cling" when releasing which it didn't do before, and sometimes didn't immediately come back in place (we're talking microseconds but as i said it's about the feeling of it.)
Anyway if this happens to you my solution was to put a little bit of copper grease on the internal circle of the locking ring, on the part where the button is is contact. Now it acts like new, better even.
Before that i tried polishing all copper parts, then since it didn't work i greased the shaft where it's in contact with the bearings. No difference either. The culprit is in fact the button itself so it's an easy fix (don't need to dismantle the whole switch if you don't want to, just unscrew the button).