EDIT- Ok, it seems that you may have already tried what I posted here upon re-reading your post but I will leave it here as I don't really have any more ideas!
Ok- yes that clarification helps! Since it is the aluminum door we are talking about and it does work sometimes I am going to assume that the tension mechanism is ok.
There is a strong possibility that pulling out the optical drive housing (very simple but if needed a video can be found at
OWC Tech Support) and moving the drive slightly back (there is a
little room for front to back adjustment in the drive bracket) might allow for freeer movement of the aluminum door. At very least, pulling the optical drive bay will allow you to check out the door mechanism from the inside to make sure all is well with the movement and that there is not some little burr or something that is keeping it from moving freely. There isn't much tension on them so it would not take much to hang them up.
Take a look to see if anything along those lines helps. I would hate to have to lug mine back into an Apple Genius Bar for a warranty fix if I had not tried that first, but that could be needed if the door doesn't pop right up with the bay pulled out! Good luck.