Have a look at this topic on the forum - it may help.
I am in the UK if it helps.
My son had the PBook kicked while at school, and then the only way it would work was if it was plugged in. Battery would show 4 lights, but discharge quicker than 15 seconds when unplugged.
I took a deep breath, and followed an Apple Take apart manual (I can send you the pdf if needed), which was a bit tricky, but not impossible.
I didn't know about Powerbookmedic.com, so got my parts from Powerbookfixit.
WallStreet Power & Charge Card - SKU PBF0308 - $24.95
WallStreet PMU Board- SKU- PBF0338 - $29.95
I also took the opportunity to replace the PRAM Battery, and upgrade the hard drive to a 160Gb at the same time (Hey - I'm not going back in there for a while!)
Anyway, as it happens, I replaced the above components, and all now works fantastic.
The only regret I have is that I didn't take it apart before buying the parts, as where the Charge card connects near the front of the Wallstreet, there is a pin connector, and this was loose!
I think that maybe I could have gotten away with pushing the board back onto the pins and all would have been ok. However, I did replace the parts as I had bought them.
Like I say, all now working well. Using OSX 10.2.8 and the 160 Gb drive is quiet.
Feel free to contact me if you have any questions.