Actually, if you have Fujitsu laptop, you are likely to have this problem since this is just a bad selection of power jack, or I could say that it's a bad design instead. Nonetheless, it has been served me very well since late last year. No one wouldn't disagree how good Fujitsu is though.
The problem is when you plugged the power jack, it randomly disconnected. You had to move the power adapter tip a bit to get it work properly again. Since I'm setting a brightness when plugged in and on battery differently, so I found this problem is really bothering me; it just keeps switching brightness back and forth any time I move my laptop. In my opinion, it is because the power adapter tip isn't that smooth at the edge and when you plug it in, it does have some trigger (to avoid loosing power jack perhaps). That, however, it's the bad part; the more you plug in and take out, the more power jack on the print circuit (and/or its mechanism) is loosing. I bet you won't find this problem with Apple Magnetic power adapter and many other manufacturers.
Well, I don't know if I'm good at explaining this situation. But I know that the picture says thousands of useful words.
You may know what is the cause of this problem now and you might have a solution already too. As you know, this is a first take; I won't do anything much since I found that soldering of DC power jack is still good enough, there is no need to take it out and find a replacement. At first, you have to get this part out. (if you don't know how to do, take a look at this. It might not cover this part truly, it gives you an idea though.)
I took a look at this part to see how to fix this for a while.
I found that if you could fill two holes I showed above to prevent DC power jack moving, it might help. You know? I tried that but no luck; I had nothing that can fill that out. Thus I came up with another idea which is finding something to put in between DC power jack and print circuit making it more solid and securely attached.
It's working beautifully by inserting a paper (in fact, I should find some non-arc thing like plastic) between them. I haven't found any random power disconnection for few weeks by now. I know this is not permanent solution, but the phrase, "If it works, don't fix it," is always a good solution. When this problem shows up again, you will see another solution indeed.