Can we talk about when a quick gear adjustment saved the day?

I was on a call for this elevator that kept jerking at the top floor. Thought it might be a motor issue, but after listening closely, I noticed a slight grinding noise from the gearbox. Took a look and saw one of the gears was just a hair out of alignment. A few taps with a mallet and some grease, and it ran smooth as butter. The tenant who'd been stuck earlier actually came down to thank me, which was a nice change. It's those little fixes that remind me why I like this job. Got any similar stories where a small tweak made everything work right?