I received this Nextech charger with a broken plug pin for repair. The broken pin can not be repaired. However, it can be replaced with another set of pins from a normal house hold 2-pin plug. This is how I repaired it:
1. A 2 Pin electrical plug (whose pins shall be used as replacement)
2. Thick connecting wire
1. Small hacksaw (or dremel)
2. Small File
3. Glue gun
4. Soldering iron
Step 1: Prepare the Broken Charger
I opened the charger with the help of a spudger (cut it open if its glued.) This one was glued only near the pins, so could be opened easily. Then I took out the charger circuit board and desoldered the existing broken pins.
Now remove some of the plastic portion (as marked in the image) to make space for new pin block. This step may be different for you depending upon the charger shape and the shape of the pin you need to fit.
Step 2: Arrange the Replacement Part
I used a 2-pin house hold plug to source the pins. Open the screw of the 2-pin plug and take out the block having two pins. Rest of it is not needed.
Step 3: Solder, Glue and Finalise
Solder the new pins to the board using a thick gauge wire (thickness should be similar to the one you removed.) You may need to position the board and pins on the bottom part of the enclosure before hand, using a few drops of hot glue. Once the soldering is done and board and pins are positioned correctly, fix the top portion of the charger enclosure. This may simply be hot glued or joined with your favorite adhesive. You may need to fill in glue at some places to fill the gaps. After the glue is dry, cut the extra glue with a knife. Its done!