Install new hard drive on old Compaq DeskPro from around 2000 with a Pentium 3

Question

I recently scrounged an old abandoned Compaq DeskPro with a Pentium 3 and 256 MB of RAM. The only thing missing was the hard drive. Anyway I got a hard drive for it, but I can't figure out how its supposed to be installed, or how the last one was removed. The case is one of the old fashioned ones which lies horizontally and I only have access to one screwhole for the hard drive. I'm hoping someone has experience with these older models and could help me install the hard drive. Thank you

EDIT: Here's some pictures

1) This is the interior of the hard drive bay itself (Yes, the image is at an angle).

2) This is a picture of the one hole I have access to I would like to point out that it's too small for a hard drive screw

3) Here's a picture with both the hard drive bay and the screwhole I have access to with the floppy, zip and dvd drive shown to the right

The green thing on the top is used to hold the floppy, zip drive and dvd in place and I think it has something to do with the hard drive bay but I'm not sure what, other than blocking the only reasonably sized screw hold from being usable.

EDIT 2: I double checked how snug the hard drive fits into the bay and I found that it has at most 0.1 cm clearance meaning any clip would have to be really thin and snap into place. If someone has a picture of the clip, that would be greatly appreciated (though I doubt it sadly).

Answer 1

I found the answer at the hp support site, hp.com/support by searching "deskpro en". However, it doesn't quite make it clear, so I've got some pictures on how to do it.

1) Put the screws in the hard drive first.

2) Slide the hard drive into the slot in the case. The screws should line up with the indent and the holes in the drive cage

3) Push the green bar to the right and slide the drive the rest of the way in. Release the bar and move the drive until the green bar slides into place and the hard drive is secure.

Only slide it in as far as the picture shows before pushing the green bar.

Once you have pushed the green bar to the side, push the hard drive further in. Release the bar and push the hard drive until the bar slides into its original position and locks the drive in place.

The hard drive is now installed into the case of a Compaq Deskpro EP.

Answer 2

It's possible that there are supposed to be rails that screwed onto the drives, and then those rails would slide into the channels (labeled 4 and 5) and spring-lock into place. When they removed the old drives, they didn't bother to remove the rails and put them back somewhere you could re-use them.