I'm definitely not the only one who wonders about this sometimes, so I'll throw it out there to the general populace to see if there's a real answer.
I got my goodies from YetiSeti today and have started having a play. The Amigas worked pretty good first pop - one's perfectly operational, the other seems a little flakey on the floppy drive front. The Ataris were both perfect. But the PC10-III... lord help me...
So the machine runs alright - it powers up sweet although had flickering characters broken video output when I started. Turns out the last owner had fitted a Microsoft InPort mouse card and an EGA graphics adapter. After removing these erroneous extras, the machine fires up great - except the hard disk wouldn't fire up correctly. It spins up but the head stepper sounds like there's interference. I've tried loads of tricks to get the drive responding, but no dice. I even tried the near identical WD drive out of my A590... it was even worse, it appears to have stuck heads and won't spin up.
Now the A590 that doesn't worry me, because it can use SCSI. But the PC10... it uses a fairly specific looking interface. It's early WD, what is branded by Commodore as 'XT-IDE'. It's some form of ancient 8-bit IDE interface that's incompatible with more traditional 16-bit IDE. Curses!
What I would like to know is, is there an effective replacement part that can be used in these scenarios? Clearly the 16-bit IDE units won't function as half the bus is missing, but is there anything else that could be used? Information seems sporadic at best...