Thanks Jim.
Neither pump nor engine has seen after-run oil, WD-40, ATF mix or anything.
I only use 0-5% nitro and drain it at the end of the day. None of the fuel lines are soft and like I said, only a hand full of flights last summer then sat till now.

Could this 120 have too much crankcase pressure and blew the diaphragm?

I would assume this is how they fail?

Is there anyone out there with years of service from one of these?

Thanks, Kirk