iMac G4. cd loading issues

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?