I got a Slide-It arcade off a friend, he said the machine was dead. I goofed with it and came to discover that the 3.6v battery on the mobo had died, which was causing the PC to reset to defaults and when it was booting it was halting on all errors, so no keyboard meant it wouldn't boot. There's two VGA outs on the graphics card, connect a PC monitor to the unused VGA out to see the PC boot screen, you can see if it's halting on the keyboard error. Replace the battery and then go into the bios and set it to ignore all errors. I know this isn't exactly what you were talking about (bad hard drive) but I thought I'd mention it.
The Slide-It has a security dongle that plugs on the back of the PC, I'm not sure if it's linked to the hard drive or the PC or what, but it's definitely matched to something.
I have a spare Slide-It hard drive and security dongle (pulled off a spare computer that came from a demolished Slide-It) somewhere, I'll try and dig it out and see if the hard drive/dongle work on my Slide-It machine.
EDIT - I found the hard drive/dongle, will test it on my Slide It machine. Will also try duping the drive and see if it'll work in my machine, if it will I can just dupe a drive n send it (if I can find the box of spare hard drives).
Does ANYONE have the mythical Slide It 3 game version out there? All I ever see is the two game version (which I and everybody else seems to also have).