The first thing to do in a case like this is clean the heads of all the drives, both the scope and the PC. For this, you need to find a floppy cleaning disk. If there's no cleaning fluid with it, just use a drop or two of isopropyl alcohol.
If cleaning doesn't cure the problem, as CJay said, you need to make sure that the suspect disk is the one that's out of alignment. Since alignment disks are impossible to find, the next best choice is an installation floppy for some software package. Those floppies had a reputation for being cheap since they were often only used once. Try a few. They should be readable on both drives.
Ed