I learned to program on that model machine :)

Same happened with my PC1640HD and its 20Mb drive. Looked almost identical when I also pulled it apart after I'd resigned myself that the drive was dead.

I'm suprised that drive worked as much as it did initially with the platter in that state!

It's a shame when the drives fail that way =/ The same thing happened on that Archimedes A440 I restored. I suspect what happens is a small piece lifts on the surface, clogs the head, head proceeds to dig up the rest of the disk =/ Either that or the head has something on it (plastic) that disolves with age, and the head just starts to tear up the surface... Might be worth taking a drive like this to bits, before its powered up to inspect the disk surface, and the heads, before that "first power on in 20 years" - but the chances are, someone else powered it up already... And of course, it could just be the disk surface itself that has "degraded" over the years which starts the destruction process.

This is a lost cause. This is the classic head crash. There's no magnetic media left on this platter, it has all been ground off... Very unfortunate.