California Tools Compressor - Valve causing breaker to trip?

These are great oil-less air compressors and they are very quite for what they do.   After years of service, this one started randomly tripping the 20amp breaker but would work most of the time to bring the tank up to pressure.

After taking the head off, I saw that the inlet check valve had a chuck of its metal missing and thereby causing it to leak compressed air.  This probably caused an air-lock situation on one of the pistons which caused the motor to bind up which then tripped the breaker.

These thin pieces of metal are a whopping $40!   But, so far this $500 California compressor has been worth it!   I don't know where the metal piece went but it's working again.