Hot take: that clicky Canon AE-1 shutter squeal is almost never the mirror box, and I proved it on my own bench
Three weeks ago I bought a beat up AE-1 off a guy in Sacramento for $45, and it had that famous squeal, the one that sounds like a sick bird every time you fire it. First thing I did was pull the mirror box out, because that's what every old forum thread says, and there was nothing wrong with it, the gears looked fine. Then I read a 15 year old post from a retired tech who said the noise is the mirror brake and the shutter release magnet needing a drop of oil, so I put the box back, took off the bottom plate, and lubed both. The squeal went away in about 20 seconds of work and I felt like a complete idiot for yanking the mirror box first. Two more squealers came in after that, a Pentax and another Canon, and the same quick fix worked on both. I get why people go straight to the big tear down, it feels like a real repair, but honestly it's costing people hours for a job that takes a few minutes. Does anyone here actually find a bad mirror brake when they chase the squeal, or is it always the oil points for you too?