Help! CD loading issues iMac G4

I have an iMac G4. Its having real issues loading cd's. The tray slides in fine but when it tries to read cds it starts whiring and sounding as if its shifting the cd around. So it clicks for a bit and then spits the cd out. DVDs are loading fine though. And occasionally a cd will load but very rarely. Whats going on? Is there anything I can do?

I don't know if this an option on the iMac drive, but are there those little tabs that you can slide over the edge of the CD to hold it in? I know on many CD trays they have them. That has solved the problem for me before.

Cheers for the suggestion Jeff.
Unfortunately I dont have any clips that do slide down. And besides DVDs are still loading fine so I'm still very confused.