It sounds like sOfus is someone you should get with about this, but I am really amazed that with heat, smoke, and non-performance that you are still using it and taking a chance on torching the entire device. Wouldn't it be easier to put it in the shop? I am assuming of course that it is beyond warranty etc.
Since you cannot immediately SEE any arc marks or melted cord, is it possible some piece of metal debris has gotten lodged near the connector, and it is jumping to that?
What is the plug looking like is it male on the cord end into a female connector, or the other way around. If male on the notebook end, is it possible on of the prongs is lose or broken?
Actor Kevin Kline was asked once (Actor's Studio) how he can play his comedy rolls with such repeated and consistent passion. His response:
"I don't know, I just can't imagine not being happy."