Help with DVD Mechanical Problem...

I have a DVD Burner (NEC) which up until recently was working perfectly
and it's less than 6 months old. I took it out of my case then put it
back and now it won't work. It powers up and I can hear it clicking
similar to the sound of someone intentionally clattering their teeth
together. It lasts for a second or two then, after a short while, it
usually repeats. It doesn't matter if there is a CD (or DVD) in the
drive or not and I have no trouble opening and closing the door. In
fact, it makes this sound during boot.

Here's the catch... when I had the DVD rom drive out of the case (still
powered), I inadvertanly opened the sliding door while the drive was
upside down. Is it possible that when the drive opened upside down
some sort of catch, spring, or something poped out of of place?

It certainly sounds like a mechanical problem.

I opened the DVD rom and carefully operated it. I witnessed it take a
CD and the carriage mechanism moved forward to the center core. It
clicks when the carriage moves to the center core but I'm not entirely
sure where the clicking is coming from.

The problem is, I can't find a good website with diagrams and pics so I
really don't have a reference for the internal parts I'm seeing.
Troubleshooting sites and faqs don't seem to help. I'm not even sure
what newsgroup to post to for this kind of question.

I'm not afraid to buy another drive if I need to but this really sounds
like a mechanical (dare I say SIMPLE mechanical) problem. Almost like
someting is being prevented from engaging the CD.

Anyone know a solution? Any good links? Suggestions for a better
group to post to?

Thanks if you can help.