I'ld try to find a replacement diskdrive, but that's just me. Replacing the diskdrive is about as simple a repairjob as you find on the A600, so you could give that a try.
And your guess about your old disks still working is as good a guess as mine. I have disks with files on them still working flawlessly after 20 years regular use. Other disks have failed within weeks of purchase... With luck, most of your disks will still work, but you can only be sure after trying it.
