Thanks. I did bend the copper bit the top read head is attached to when I was greasing/degunking the drive, but I carefully pushed it back into place and verified with a floppy that it's making full contact with the disk. It may still be related to a problem with the read head not making contact or not reading properly. I'll try cleaning it.
I've got another drive to disassemble and clean, so we'll see what happens.
I've got another drive to disassemble and clean, so we'll see what happens.

