I have a fridge that I believe to be 20 to 25 years old. (It came with the house.) Not always, but sometimes when it finishes its cooling cycle, it makes a loud rattle-like sound, almost like three or four shots of a machine gun. It's quite loud when it does it, especially when I'm trying to sleep.
The fridge itself is cool inside. I've checked it for level, and it's perfect side to side, a hair low in the front. There is no ice maker.
Is there anything else that can cause a fridge to make a rattling sound? Is it possible the fridge is on its last legs?