Tim - below are a couple pics of my plug. I have now re soldered this one twice. The first time was about 6 months after I purchased the Etrac brand new which was about 6 years ago. Then I re soldered it again this past summer when my Sunray headphones needed service. The UR30 minelab phones are my back up.
I would open this plug up for you but if I do that I risk breaking a connection. So I will just explain it. The brand is Neutrik. I recommend the 90 degree plug which is easier on the wire which means that it will likely last longer. I believe you use an Etrac so be sure to get the STEREO version of the plug.
Now the fun part. You will need to solder the 3 tiny wires to the connections on the plug. I figured out what wire goes where by turning on the machine and putting the wires in place until I got a tone as my kids waved a penny over the coil. Once I figured out which wire goes where I took a wood burning engraver and some solder I had and did my best to solder it up. It was not the best but this lasted me a couple years until I got some decent head phones. Then last summer I took this to a friend who does some electronic soldering and has a small soldering kit. He did a much better job than I originally did.
So I recommend if you do not have a small soldering kit or if you eyes are as bad as DaddyDigger's and Digger Don's (man those guys in their videos make me laugh as they guess as what date they just found) then find someone that does. I just typed in Neutrik 1/4 stereo plug on ebay and there are many available from $7-20. Maybe your IT department at your work has a small soldering kit?
Hope you can fix it with out spending more than $15 or so which is much better than $125-150 for a new set of headphones!
Jared