Looks like Huma is now selling a replacement gauge for the Crown and Royale series. The stock holes for the gauges on my Crown are 26.53mm and the Royale is very similar. They have the larger easier to read display and a brass external body so they should hold up well. From a personal experience over the years the FX gauges are too fragile and easily damaged beyond repair. When your taking off the stocks and the plastic gauge housing pops off something needs to change.
Good job Huub
Jimmy
https://www.huma-air.com/Fx-replacement-pressure-gauge-26-mm-round-model
Good job Huub
Jimmy
https://www.huma-air.com/Fx-replacement-pressure-gauge-26-mm-round-model