Something got in the compressor... so it'll run for a bit and then the light standard humming becomes VERY loud until the lights flicker and all that's heard is the sound of a seized electric motor trying to turn... which is the actual case.
Didn't have the room for a bigger fridge yet.
Now that I do, everyone selling an older used fridge must have fell and bumped their head, because... like $200 for a 1970's Frigidaire with a no-defrost freezer that's behind the door? Fuck that.