Ah yes, C64 floppy drive “headbanging”.

IIRC this is because rather than ship a design with a limit switch or any position sensing at all, the drive software just rapidly slaps the read head home a bunch of times to ensure it’s properly aligned with track zero. I have a hard time believing this was to reduce part count, because the drive itself is a whole-ass 6502 computer; the sale price also reflected that. Instead, I think it’s a software fix for a “sometimes an issue” hardware problem.