Good news! Reflowing/resoldering fixed both machines.

Now I have floppy woes. I have a 128k and a 512k that have broken floppy drives. When you try to put a disk in, the disk doesn't articulate down no matter how hard you press. So I took apart the 512k's drive and was able to force the disk to engage by pulling the manual release mechanism in the opposite direction. I powered it up and it seemed to be spinning the disk, but soon I had a burning smell . So I think I ruined one drive.