My beloved Agfa Isolette II is "buggered" - I think. The shutter cocks, but stays cocked even after much coaxing, tapping, shaking, and (inevitably) shouting. It just sits there waiting for something to happen, but refuses to tell me what I should be doing.
I'm not sure if this is a common problem or not. If I'm feeling plucky one day, I might take it apart (plenty of guides online for doing this) and see if I can fluke a fix.
It'll be a damn shame if it's permanently broken. I quite like how compact it is for a 120 camera, the photos I've taken with it came out amazingly well, and it looks awesome. But it is about 55 years old, and considering it was $25AU in a junk shop, it's amazing it even still worked.
Here's hoping it's only a hiccup on an otherwise uninterrupted long-term photographic partnership.