The equipment I love the most- ARC is also the most problematic and finicky. I discovered that preventative maintenance stops the fireworks. W Zane Johnson had the notion that his customers were all techies. Read the owners manual from his ownership era and it tells you how to bias your amp with a multimeter, etc. Yeh right. I have no business poking around with a metal probe in an amp with literally lethal voltage in the power caps. Plus I don't own an oscilloscope or tube tester.
DBX equalizers seem to be pretty problematic as well.
Japanese stuff is pretty much bulletproof but time and current ruin capacitors no matter who makes them.