whats wrong?

when i try to get the cd tray to go in and out, the protection message comes on and it will not open. It does turn however. I opened it up and cannot see anything that is mis-aligned, what can be the problem? I am afraid to do anything except what is obvious, which there isn't anything obvious.
Samsung HT-DB600 Digital Home Theater system.
Older unit but has not been used in several years. trying to get it going again, the tray did operate, but my hand caught it and may have done something when that happened.

Connie
November 2017