HP ZV5000 power problems

I have an HP ZV500 Laptop, its about 3 years old or so, and lately Ive been having problems charging it. Now, I know its not the battery, because the battery will hold a charge, for a short time. The problem is, when its plugged in, it does not always charge.

Often I will have to pull the plug out and plug it back into the back of the laptop several times before it will provide continous power, and even then it will randomly turn off, anywhere between a few seconds, to a few hours. I know for a fact that the problem has to do with the DC connector, as my mothers laptop had the same issue, and when she sent it back to HP it was repaired and sent back. The issue is, my warranty has long since expired, and theyre wanting to charge me $700 for the repair, which is a bit ridiculous.

What Im curious about, is if anyone has had this problem, and if they know what the repair process was. Im pretty handy with a soldering iron, and the hardware part of electrical work, so long as its not overly complicated. I actually just took my laptop apart, and now have access to the DC jack so I can solder or replace it if needed.

What Im hoping is, that the DC jack is just bad, and needs to be replaced, or if I need to replace the whole motherboard. Does anyone have any suggestions what to look for to determine what the problem is? Any help would be greatly appreciated!