If your selector is like mine, you insert a metric allen wrench in the flush screw and twist CCW. The button cap does not come off. Lift up the whole lever as you unscrew it.
RV-8 QB Titan ECi 191HP XIO-360
WW200RV Dynon D180 HS34 AP74
GNS430 SL30 GTX327 PS8000B Navworx ADS600b
"Pilots are alchemists... we turn gold into lead."