My XPS M170 laptop seems to have a connection problem.where i insert the power jack into the back of the laptop it fails to charge battery however the power meter states  i have ac power,however if i move the jack or touch it in any way it goes back to battery and i lose power.can someone tell me if the connection is a motherboard connection or an adaptor one? i need to take this into be fixed but if it is a big job then it wont be worth the cost.please advise.

regards

Steve