How Can I Fix My Xbox 360 Tray That Keeps Getting Jammed Inside?

I have the 1st model of the xbox360, bought it in 08. Everytime I go to open the tray my xbox makes the sound like it's about to open then it says reading and back to open tray. The weird thing is that it only opens when there is a disc inside. When there's no disc, because my brother sometimes forgets to leave the game disc in, I stick a paper clip right under the tray where there's like two gaps or holes. I've noticed that what I'm really doing is pushing the gear looking thing for it to open. I'm wondering what can I do so I can open my tray normally and not with a paperclip when there's no disc inside. I basically want a permanent fix.

probably best to replace the drive,its only a matter of taking cover of and taking out old one and replacing .
Hers a youtube video that will help

http://www.youtube.com/watch?v=5XiYSV9ztVU