Does reseating the daughtercard do anything for you?

Yeah, I'm actually about to give that a shot right now. :-)

In my quest for a cheaper jack I came across this:http://www.computekinc.us/dell_project.htm which apparently converts the weak jack to a better design.

I also came across a possible alternative jack in the form of the Hirose RP-34.  I have requested an engineering drawing from Hirose and will let everyone know if this one will work.

Fixed. Old DC jack was indeed bad. Soldering in a new one was the solution.

After a lengthy delay ordering and receiving the replacement jack (purchased through one of the ebay auctions referenced in this thread), I have desoldered the old jack, soldered in the new one, and booted the system with success - the battery is charging as I write this, 18percent and counting...

More details, in case someone cares:
The old DC jack had an internal fault of some kind. While it was still soldered on to the little connector-board, I tested the pins (solder joints) with the ac-adapter plugged in and did not see 19.5v between any two pins (didn't find more than 0.5v anywhere). After replacing that jack with the new jack, I found the desired 19.5 volts between either of the two hot pins on the outside back of the jack and any ground point (basically every other pin on the jack is a ground (including the jack housing joints). Also note that I tested the old jack when completely removed from the board and did not find the 19.5v between any of the pins; thus the fault was indeed completely internal to the jack itself.

As far as the actual desoldering, it was a pain, though the difficulty is likely related to it being my first time desoldering something from a fine printed board. Anyways, I used this for a desoldering iron: http://www.radioshack.com/product/index.jsp?productId=2062731&cp=&origkw=desoldering&kw=desoldering&parentPage=search
Cheap and effective. There was no clear way to heat-sink the board, so I didn't worry about it - no ICs on it anyways. I was a little worried about having to pry against the substrate (slightly deforming the board) while applying heat to a few of the joints, as it proved impossible to vacuum the solder out of the jack-housing joints. I have yet to test the other ports found on that board - crossing my fingers on that one.

All in all, a successful repair - paying an obscenely overpriced $35 for a $1 jack sure beats forking over $300+ to replace a perfectly good motherboard in order to get a new jack...

Thanks to all for the help.

Still a good thread. I just repaired two Inspiron 1150's that had been gathering dust for almost a year!

Excellent - glad someone else found this useful. Also good to know an additional model on which this repair can be effective...

If you end up giving it a shot on your D600, please post your results in this thread. It would be nice to build a list of models for which this problem/resolution applies. Thanks.

Well, if you can't do the repair yourself, a new motherboard will probably be the cheapest solution, actually. First of all, I doubt that you're going to find a shop willing or able to do a board-level desoldering/soldering repair. And if you DO find a shop willing to do it, it's going to be at least a couple hours labor, which will quickly add up to more than the cost of a new motherboard (which should take under an hour to install). Bottom line: If you can't do this fairly time-consuming repair yourself, you're going to spend a couple hundred dollars getting the computer fixed, one way or another. It's really a shame that this is seemingly a common problem which Dell will not resolve for their customers via a recall.