CD/DVD Drive is popping out

So, I have a very old Dell Vostro 1720 laptop. It has gone through the wars and so is getting on a bit. It has lost a caps lock key, and is generally feeling old.

The main problem is that it has lost the cover to the CD/DVD drive, it is just the edge and does literally seem like just a cover. However, it also does not shut properly. This happened a while back but I have never really needed it properly. When I shut it, it just pops out straight away again, i shut it a few more times and it pops out again and again, eventually sometimes when I try random different insertions it stays in, but then with a slight movement of the laptop it will pop out again. I think most CD/DVDs work in it, when I get them in and keep it still, but am not 100%, it makes all the buzzing noises and all.

Recently I have been trying to do a PC Restore using the Dell Windows CD you gave me, however, when i start it up with the CD in and select boot from CD/DVD it just makes a load of noises, looks like its gonna do something, then after a while just goes and boots up normally.

Now I know most people here, especially Dell Sales people, will just say buy a new drive, but unfortunately being a student this is my very last resort; the resort I take probably after buying a new laptop, as it is so old.

Any suggestions as to what might be going wrong? or if you think it is going wrong? I was thinking maybe that it is working fine  when it does get in, and there may be  a problem with this specific CD for PC restore instead.

Many Thanks,

Benji