Here is my Story/guide on how to fix your open tray problems.
I found out how to flash the fireware to play backups so i opened up my Bro's Xbox and found out it was a Lg 78 DVD drive and once the first fireware came out we jumped on it, like most people. We got the Xbox playing back ups with out any issues what so ever.
One day my Bro's xbox just packed up and started making weird noises and wouldn't read ANY DVD (Orignal games, Movies or Burnt games)
Reading on this forum found out that the "OPEN TRAY" issue was very BIG. So read alot about it and desided to do the Plastic trick (as shown here http://www.360mods.net/News/article/sid=71.html) I pulled the xbox apart again and stuck the plastic on and then put it back to gether shame didn't work We still had the same problem.
Well this week i desided to take the whole thing apart and look at what is going on and also try the rubberband trick. Which didn't work either
So i removed the rubberband and then tried to load a DVD game and see what happened when it is all apart. Silly me forgot to remove the "plastic clip" (see image 2) that holds the DVD in one place so the DVD went flying (i'm talking about the clip on the inside of the top cover of the DVD-ROM Drive) Once i removed this it started looking better the DVD would spin but still not grabing the DVD right so i took apart another cd rom drive to look at other stuff and i found that the magnet from the centre of the drive was missing (Image1 BLUE SQUARE) i looked on the Plastic clip and there was the magnetic circle. I removed the Magnet from the plastic clip (which was hard to remove) and glued it back on to the centre drive. waited a while for the glue to set and put it all back to gether. tested it out and is working like a clock work Orginials and back ups
I've posted some pictures and hope this makes sense.
Image1 BLUE SQUARE
Image 2 (i know it is small and crappy)
If you find or can get a better picture let me know and i'll put it up
(you can see the Plastic clip on the youtube Video http://www.360mods.net/News/article/sid=71.html)
Please note that I never removed the Plastic trick. Also Image2 isn't really the top of the Xbox 360 DVD drive top it is just an example as i didn't take any pics while fixing up the xbox
PS my theory of it is that the Xbox gets really hot and the glue or plastic that is holding the magnet down has unstuck it self and it gets held on to the top with the "Plastic clip" this can cause problems with both modded and not modded Xbox 360s.
*IMAGE 1 from JayQue*