I have a fridge that is not too old (7 years), but they don't make them like they used to. It knocks really loudly. What I've read is that the compressor is knocking around due to the springs holding it in place failing. I can't figure out if it is something I can change. The people who write about it just ended up buying a new fridge, but I'm not sure if they tried to quiet it or not. Supposedly, it doesn't affect the fridge function. It's just really noisy everytime the it cycles off. I've opened the back up and I can get to it, but I'm not sure how hot the thing can get and I don't want to stick a towel back there to dampen the noise if it is a safety issue (OK, I would, but my wife draws the line there).
Thanks