CD stuck and making noise

Hello!, i have a 27 inch imac from mid 2010.

Some time ago i had a problem in wich i put a memory stick in the cd reader accidentally, as u know, the cd slot on the imac take the cd inside and u cant take it off by hand. so what i did is open the imac using the tutorial from this page, and i unsrew the cd player and i took it move it until i reach the memory stick stuck indise. then i screw it back in the imac and i closed, but since that day some cd's (not all) that i put in the imac stuck inside and i have to use a clip to move it a little to make it eject.

the question is: it is possible that i screw the cd player too hard and that make it moved or misplace and that cause the cd's i put to stuck inside?

other problem i have is that when they read some cd's it make noise. what can cause all that, maybe somthing i did when i opened the imac?

Thanks !