Grab a multimeter and place the red probe on pin 9 (3.3v) and the black probe on pin 2 ( ground) and set your meter to 20 DC Volts like in this pic ...

It should read around 3.3 volts if the headerpin is working ! If you don't have a multimeter grab one from Radio Shack as they are very cheap these days !
Maybe some pics of the pinheader would help ? But in any case you will have to heat it up and adjust it , maybe bit by bit. Or grab one pin at a time with plyers and heat the other side and pull the pin out completely ( with the xbox motherboard removed and in your knees ! )
HackDaBox !