Started happening a few years ago, unclear whether it has gotten any louder or whether there's anything that makes it better or worse. I don't think it was this bad when new, though.
Functionally, fridge still seems fine. It was off-the-scale efficient when I bought it in 2000; it's probably average or below by today's standards.
I've gotten used to this clunk/thunk/thud noise and mostly don't notice it. I've assumed that it's the compressor being pushed back a bit as power is removed, or something like that. But it occurs to me that one of you might know what it is and whether it can be quieted at all; I now have a guest bedroom next to the kitchen and I'm sure visitors would appreciate not having to hear it hiccup quite so loudly.