Thanks for all the responses! I have one 2400c completely disassembled, and have found one bad fuse out of like 11. I'll be looking into replacing that. Its the fuse right by the HD connection, so I'm betting that is why this PB won't spin up an internal drive.

I'm going to try to research some more info about the hard drive particulars once I get this fuse replaced.

I'm taking apart PowerBook #2 now.