The power plug in port you refer to is the DC Power Jack.
The AC adapter (Charger) converts AC electricity into DC electricity.
DC electricity has two poles. Positive, and Negative.
(Just like on a D cell flashlight battery)
The center pin of the DC Power Jack is the Positive connection.
The outer metal spring-like pieces, on the inside of the cylindrical shape surrounding the center pin, are the Negative connection.
(The pieces of spring-like metal, all connect to the Negative connection in the DC Power Jack)
Example of a replacement DC Power Jack, for the Asus Eee PC 1005HA Netbook,http://www.batterysupport.com/asus-eee-pc-1005ha-jack-p-303527.html
Cannot agree with the replacement instructions they offer, at the bottom of the page.
Not everyone has access to a hot-air gun. A 25 Watt soldering iron, and Desoldering Braid, is better, and more easily accessed ]
A few articles dealing with replacement of a DC Power Jack,http://www.laptoprepair101.com/laptop/2007/12/06/dc-power-jack-repair-guide/http://www.laptoprepair101.com/laptop/2006/01/28/toshiba-satellite-m35x-a75-power-jack-problem/
1) Remove ALL power. Remove the AC adapter, (Charger), and Battery.
2) Observe Anti-Static Precautions. Buy, and use an ESD wrist strap.
Electro Static Discharge.
(Average cost is from $3 to $6. Connect the alligator clip to a good ground source.
I connect to an unpainted surface, of the metal frame of an open, empty desktop computer case.
If you wish to proceed in replacing your DC Power Jack, and need guidance, post back in a Comment.