Hello friends, i came across something last week, my iBook G4's DC jack was loose and it would loose power to the machine even if i looked at it (yes, it was that bad lol) so what i did was folded a little bit of paper and shoved it above the DC jack (around the case) also depends which way you need to push the jack to make it work, after i did this with the G4 it worked almost perfectly, then i got an iBook G3 with almost the same issue, although this one just stops charging, so i folded another little bit of paper, and sure enough he works! now it charges and runs of AC even when i wiggle the cord. 
