dvd superdrive

Have an imac ppc G4 800mhz OS 10.4.10 -my superdrive dvd won't recognize dvd's inserted -it just keeps making a clicking/whirring noise & eventually spits out the dvd. but it accepts & burns CD's. problem is i can't burn any dvd's Is there some way to find the fault or some software i can d/load to identify the problem or will fix it. greatly appreciate any help.

I have the same machine, and had the same problem.
I had to buy an external burner - the superdrive was broken I'm afraid to say.