i'm thinking it might be the CRT high voltage circuit doing some creative discharge across some area, often after tons of dust offers a nice path to ground or some other part. the fans in those things do tend to give up the ghost after YEARS of constant whirling too. fans built with 'permanent bearings' really aren't permanent, the lube dries out eventually. the floppy drives are the same, they wear and the floppy disks themselves can shed oxides that will cause the heads to 'chatter' as it seeks and reads. i've known enough of them to squeal like pet guinea pigs. the capacitors of that era were good solid electrolytics, usually wet electrolytics that do fail, and their ratings slowly become dangerously close to failure. heat is their enemy, once they go, they're done for and must be replaced.
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fan i think. or could be the floppy trying to turn and the head attempting to seek to the reference point. if the unit was thrown and landed badly, the floppy drive could have loosened a few innards or shifted enough to warp the mount points. the fan may have been damaged, lost some or all of the blades. also, the fans in those things do tend to give up the ghost after YEARS of constant whirling too. fans built with 'permanent bearings' really aren't permanent, the lube dries out eventually. the floppy drives are the same, they wear and the floppy disks themselves can shed oxides that will cause the heads to 'chatter' as it seeks and reads. i've known enough of them to squeal like pet guinea pigs. the capacitors of that era were good solid electrolytics, usually wet electrolytics, but they do fail, and their ratings slowly become dangerously close to failure. heat is their enemy, once they go, they're done for and must be replaced.
i'm thinking it might be the CRT high voltage circuit doing some creative discharge across some area, often after tons of dust offers a nice path to ground or some other part. the fans in those things do tend to give up the ghost after YEARS of constant whirling too. fans built with 'permanent bearings' really aren't permanent, the lube dries out eventually. the floppy drives are the same, they wear and the floppy disks themselves can shed oxides that will cause the heads to 'chatter' as it seeks and reads. i've known enough of them to squeal like pet guinea pigs. the capacitors of that era were good solid electrolytics, usually wet electrolytics that do fail, and their ratings slowly become dangerously close to failure. heat is their enemy, once they go, they're done for and must be replaced.