Since the plastic "spring" that return button cap in only in one side, the button cap sometimes is pressed non aligned with hole and became jammed.
My solution (used ~15 years ago in a Tm F22PRO 2nd stage trigger), a small section of silicone tube (for 'glow' fuel lines), cut cut lengthwise on one side, forming a closed "C", fitted in PCB over button cap:
BTW - This unit (~1.5 year old) for some reason develop cooper corrosion in BUS and RUDDER connectors pins - that are not used (bellow right).
The silicone tube make buttons operation a bit more softer, and they don't get jammed anymore.
https://www.youtube.com/watch?v=-WUqhaDHqh4
