I have a launch-model Xbox 360, so the warranty is long since expired. For a while now, I haven't been able to open the disk tray without already having a disk inside, or using a paperclip to manually open it. This isn't a massive issue, but I move it around a fair deal and leaving a disk in the drive makes me extremely uncomfortable. So, having already done so to fix my red ring, I opened my Xbox up to try to solve the issue. I also disassembled the drive, to the point where it looks like this:

Now, with my drive outside of the metal enclosure, the disk tray works just fine. However, when I put the top half of the enclosure back on, the tray no longer works. I have no idea what could be causing this to happen, so I was hoping you guys could help me out to fix this problem once and for all. Replacement drives are quite expensive (~$30, about as much as the Xbox itself is worth now) and I don't really want to go through all the effort of flashing the firmware so I'd like to resolve this if possible. I've got my 360 naked and splayed all over the table, so quick responses are appreciated here. It's the Toshiba-Samsung drive, by the way.
Now, my 0Xbox. I just got this today off Craigslist, and it works fine except that the tray sometimes "sticks" when I try to open it. It'll eject about halfway, then I can hear a mechanical whirring noise and the tray sticks. Even when it opens fully, it clearly struggles to get past that middle point. Would opening this baby up and cleaning it out likely fix this problem, or should I be looking into replacement parts?
I did a quick google search and wasn't able to find any real solutions to either of these problems, but if there's a better forum to post this on I'd appreciate a point in the right direction.