I have a quick mill QM67 from 2012...well past 10000 shots in that time and about 5 hours of "On time" per day. since I got it I hacked in a direct plumbing lin

I have a quick mill QM67 from 2012...well past 10000 shots in that time and about 5 hours of "On time" per day. since I got it I hacked in a direct plumbing line with a solenoid, and have killed one $29 pump. However, it is probably now in need of a teardown. the brew pressure bypass valve is seized, and there is some scaling/corrosion in the brew head. I've got a machine shop, so I'm tempted to tear the whole thing apart, rewire, and replace the core electronics, but I'm not sure exactly what to do.