17" Aluminum Does Not Charge In Use

I bought a used Apple G4 17" A1013 1GHz 133MHz and slowly worked through repairs. I replaced the battery and hard drive (160 GB) and have installed Leopard 10.5.4 The computer runs very well.
But, it will not charge when hooked to a 65W adapter while in use. It discharges like there is no adapter on it. The icon shows percentage of charge is dropping while displaying the plug icon. When the computer is off it charges just fine.
I have reset the PMU and PRAM a couple times. I have drained and recharged the battery twice.
Help? Am I overlooking something obvious?

Latest shenanigans on this 'puter is that while attempting a download the battery was draining so fast I hard booted it off with 5% charge left. Apparently the battery continued to drain even after being shut down. It had one blinking light at shut down, and zero lights shortly after. I removed and replaced the battery and continued to try to charge but it is not coming up at all.