Rant: customer said his lens "just stopped working" and I found the real issue in 2 minutes
Had a guy bring in a Canon 50mm last week saying it quit out of nowhere, wanted a full teardown quote. I popped off the rear cap and found the mount screws half backed out, maybe 3 or 4 of them loose enough to shift the whole assembly. He admitted he'd been carrying it loose in a messenger bag for about 6 months, no case. I snugged them down with a JIS driver and it focused fine, charged him $15 and a handshake. How often are you folks getting jobs where the "broken" gear is really just loose fasteners from bad storage?