Vostro 1000 indicates charging but it actually isn't

My Vostro 1000 has recently been failing to charge the battery. There's no adapter warning, no battery warning, nothing. It'll indicate that it's charging normally, so I will leave it overnight to charge only to find it deader than a doornail the following day. I typically shut it down when I'm not using it, so it's charging with the power off anyway.

The battery is a nine cell Rayovac COM 10025 and the chargers are both Dell PA-90s. I know one of the chargers has a break in the communication line, but I can still get it to charge the battery if I hold the wire just right as I put the plug into the computer. The other charger, which is my main one, seems to work OK.

When this happens, the laptop will not charge the battery at all until I pop the battery out and back in. The battery is only three months old, so I shouldn't be having trouble with it. The last battery, which had to be replaced under warranty, was the same model and had lost 2/3 of its capacity in less than a year.

Is there anything that could go wrong with the laptop itself that would cause this? I assume such a fault would be on the motherboard, which (for me) is an easy replacement.