Instead of paying over $100 to have a new DC power in jack installed on my Dell notebook I figured a way to do it myself for almost no cost. It does NOT require any disassembly of the computer. The one in my guide was undergoing a video card replacement at the time. You do not need to take anything apart.
You can see in the picture that tape(!) was used to hold the plug in. Not very effective.

Step 1: Parts Needed

You need a piece of durable plastic like a coffee can lid. Cut a small piece about 1" square. Use a hole puncher to punch a hole in the center. Punch two small holes in opposite corners. These are your drill guides.

Step 2: Enlarge the Hole

Now you must make the punched hole slightly larger to accomodate the AC male plug. I used a reaming tool to do it but you could use a knife to do it. Be careful and don't make it too large. You want to make it pretty tight. I've done a previous mod on another laptop and it still is working after six months. You want it so it is very hard to pull off the plug.

Step 3: Test the Hole Size

You must make it very snug to work right.

Step 4: Final Assembly

Now place the piece on the back of the computer over the DC in hole. Using the two smaller holes in the corner drill a small hole into the notebook chassis using a 1/16" drill bit. Only go in a short distance. I then used two small screws to firmly attach the plastic. You must use screws as glue is not strong enough to hold the piece on.
You can see that I have also fixed the DC plug but that's another story!
That's it! I have to use two hands to pull the plug out now. It will stay in firmly until you want to pull it out.