iMac G3 Problem

I have an iMac G3 400Mhz model with firewire that up until recently worked perfectly, 2 days ago however it stopped waking up from sleep mode. It boots up normally and works fine but when it goes into sleep it never comes out correctly.

The usual pulsing orange light appears but when i press the button again it shows up green but there is no system activity occasionally it will shut itself off too.

Does anybody know if a PMU reset will fix this, I have performed a PRAM reset multiple times but cannot figure out where the PMU switch is. Thanks a ton.

 

yes, i have purchased a Brand new PRAM battery, I have had it wake up a few times under OS 9, but i get Kerne Panics under 10.3