When I first got my powerbook (used, a few weeks ago), you had about 30% of the rotation of the charger plug that would not charge. That gradually expanded to 100%. I took the whole damn thing apart and the only thing I could find that appeared to be wrong was there was some tarnish built up around the outer shell. I polished that off with some diatomaceous earth, touched its connectors to the circuit board with the soldering iron to make sure they were not cracked, put it all back together and still nothing.

Any ideas? Any ideas on how to test this charger/adapter? I know I should have tested it when I was in there with the dc board out, but now its too late. I don't have any other powerbooks or chargers handy I can test it with

Mine is the 2005 15" g4 1.67ghz

It's usually going to require replacing the dc-in board or the bottom case is slightly dented in that corner.