Sorry for the late reply, but I thought I'd update here on the situation.
About...two weeks ago, I went and got myself a basic 30W soldering iron 'kit' from the local rat shack. just a basic single-wattage electric iron, basic tools like a small plastic stand for the iron, needlenose pliers, wire snips, and a small coil of tin solder. Now I am very new to soldering here. This is my first real soldering iron save for the old coldheat iron I had which did diddly squat and I just tossed it in the garbage. With the help and advice of a more experience friend of mine, I went in and did some practice first. One was hard wiring a usb plug onto the battery leads of my old busted portable cd player for a hobby project of mine which came out fine though it took me some time to get the wires to hold. Second involved resplicing the power wires on my mothers CB radio and actually soldering the splices a bit so they wouldn't come loose in the car.
So once I got that bit of practice in, I did the VERY careful attempt to at least try to further solidify the connection the original DC jack has on the motherboard despite the fact it already seemed real solid to me. All I really did was added just a tad bit more solder to the joints on the underside of the board whereas originally there didn't seem to be any and they were just held in by the bits of the dc jack being twisted enough to keep it from moving out of the board.
First time I tried this and tried booting up, right away I knew something borked up since the brand new ac adapter I have, it began melting the plastic on the tip of the barrel adapter and it would neither register as charging the battery or boot up without the battery. So I immediately removed all power and tore it all apart once more and spotted there was a small bead of solder lingering on the bottom side which could have easily shorted against the metal plating inside of the bottom half of the case. knocked it off, rechecked if there was anything else that could short. all looked fine, put it back together, booted up fine.
Now comes to where I sit at now. All is working peachy UP TO a point. With the new ac adapter I have yet to have a single problem with wiggling the jack causing it to intermittently lose power. The only time it does indeed lose ac power is if I pull the jack out the whole way or unplug from the wall. I tried the original ac adapter ONCE while in the car off the inverter I have and I expect it to be related to the jack being a bit loose on it anyhow, but it still did the wild intermittent flickering as before.
Now here's the /REAL WEIRD/ issue: Anytime I do lose ac power at this point in time, no matter of reinserting or wiggling the jack will get it working again. The only thing I can do to regain AC power is to shutdown altogether, pull out the battery (well, I dunno if pulling the battery is necessary, but it's the only surefire way of testing if the laptop is actually pulling power from the AC adapter.), plug the ac adapter back in, turn it on, once up with ac power only, pop battery back in and all is well. But by no other means will it re-register the ac adapter with it still running.
Also, as another interesting detective note: I have a nextel iDEN phone here which is notorious for causing interference like patterned static over certain speakers during use, and I have also noticed it is also capable of causing the laptop to 'de-register' the ac adapter even if it hasn't moved anywhere at all.
Since the laptop works just fine still in a fairly stationary position, I haven't bothered to tear it down again to investigate, but I'm due for a decent car trip saturday and I require use of the cellphone for tethered access during that time so sometime this week im gonna have to tear down and check and try to repair my goofup. Any other bits of advice I could be given here? I'd much appreciate any and all help. This is seriously beginning to annoy me.
EDIT: /ALSO/. Although I somehow doubt how it's all related, I did add a minor mod during that time which was an external SMA jack replacing the internal antenna on the left side of the lcd under the bezel. Basically all I did in that case was desolder the little 'scrapmetal' piece from the wire coming from the minipci card and spliced and soldered it into the end of the SMA pigtail and wrapped that joint tightly in a small bit of electrical tape. the jack itself is mounted inside the screen bezel still about 2 inches from the top. About the only possibility on this I can guess on is the mod job I did is pulling in more interference than desired and is sending that off to the dc jack area of the motherboard which is somewhat adjacent to the place where the lcd cable and antenna leads pass through the hinge.