I was able to get the entire mirror box out with the attached QR assembly fairly easily after removing 2 screws underneath the screws holding the viewfinder prism to the chassis on the back of the camera. The problem was exactly as the manual had described - basically the "QRL-2" lever was slipping from the groove where it connected with the "QRL-4" lever. The QRL-4 turned out to be the only piece of plastic in the whole assembly, which seems like it was a bad choice, as the lower part of the groove had been eaten away by the metal tip of QRL-2. There was no way I was going to be able to bend the QRL-2 tip as the manual suggests. I thought about trying to shim the plastic groove somehow, but after actuating it a few more times, the plastic QRL-4 just broke completely. I suppose it was already on its last legs. I don't think there's even any sense in trying to replace the QRL-4 at this point, but it was a fun little foray into camera repair.
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