Cannot get my disc drive to eject. It whirs like it want to eject but nothing happens. Any suggestions on how I can fix this?

Try depressing the mouse button while booting. That may open the drive.

Can you tell us more about this computer. There are a number of models of "G3 Power PC" with different form factors and service accessibility. The model type affects any further advice we have on trying to fix it at home.

OK, what you have is an iMac G4 17-inch USB2.0. Good work.

Unfortunately, that model is among the hardest to service at home. Getting one apart is a job of modest difficulty; reassembling it so the heat dissipation system works properly is more difficult. Many have succumbed to heat-related failures following improper reasesembly.

Did you try my suggestion of booting the computer while depressing the mouse button?

When you start the computer can you hear a short sound from the optical drive?

If you put a light fingernail pressure between the tray and the computer case, does anything move?

If you need it serviced professionally, unfortunately Apple considers that model obsolete and will not work on them. You'd need to find an independent repair shop that really knows G4 iMacs.