To second ChasC, it's actually getting pretty hard to find burnable media that works reliably in drives of that vintage. If your OS CDs are burned copies, well, the drives might actually work fine. (Okay, maybe the one that reads audio CDs works fine.) Have you tried with real "pressed" CDs?

Seriously, the problem is getting so bad is that the last three times I've messed with NetBSD on my old Sun boxes I've ended up biting the bullet and setting up a netinstall server to get things going because of problems with burned CDs. Had to go with Netinstall to get Debian on an old 1997 vintage lunchbox PC as well, its laptop-sized CD-ROM drive was completely useless for anything modern. (With funky and borked BIOS support the icing on the cake.)

By bridgeboard you mean the board between the JAE 50 pin of the drive and the larger 44/50 pin that goes to the motherboard (through the metalring)? JAE 50 is the common connector in laptops, it's basically 40 pin ATA (1 to 40), 4 pin power (41 to 44) and 6 pin option pins (A to F), in this case they are used for sound and reset IMHO. Pretty common.

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Yes, JAE 50 is common. The 50 pin ribbon cable that goes from the JAE-50 adapter board to the motherboard in the Mac is *not*, that's what I was referring to. (It is of course easy to find JAE-50 to 40 pin desktop IDE adapter boards, so I was describing a possible situation where you couldn't get a laptop drive to work with Apple's adapter board and cabling but it *would* work with a generic adapter.)