That old Minolta in Cleveland that made me buy a shutter tester
Back in 2012 I had a customer bring in a Minolta SRT-101 that had sat in a basement in Cleveland for 20 years. The shutter was stuck and the light seals were basically dust. I spent a whole afternoon just cleaning the guts and figured I had it right, but the curtain was still dragging at 1/1000. That's when I realized I had been eyeballing speeds for years and never actually tested them with a shutter timer. I bought a $60 used tester that next week and it completely changed how I check every mechanical body that comes through my bench. Has anyone else gotten burned by trusting your fingers instead of a real measurement?
Learned that same lesson but from the other direction: cheap testers can lie to you too, so I started shooting a roll of slide film at each speed and checking density on a light box. Film is the only judge that matters since it's what the camera actually has to expose. A tester gets you close but the roll tells you the truth.