Ipod Touch headphone jack problem (w/ 4th gen.)

I got the 4th generation Ipod Touch in December of 2010. I listen to music with headphones a lot, meaning I plug them in and unplug them from my iPod many times. About a year ago, one pair of my headphones started to lose the main vocals of the music I was currently listening to unless I had the wire at a certain position. I thought it was the headphone wire but every other device I used those exact headphones with worked perfectly. Now, I can ONLY hear the background tracks of a song (no vocals at all) no matter what way I position the cord. However, (this is the part that annoys me) if I plug my iPod into a cable that is NOT permanently connected to headphones of some sort (i.e. a standard 3.5mm audio cable - 3.5mm-audio-extender-male-to-male.jpg) it works fine. I've found that the difference between the ones that do work and the ones that don't is that the rings on the headphone jack (Four-pin-3.5mm-plug-wiring-diagram-1.gif) are slightly closer to the tip than the ones on the cable. This had led me to believe that the connectors in my iTouch headphone jack have fitted to the headphone-style connection, causing a loss of firmness on the plug. If you have read this far, I thank you for that and now ask for your assistance. What should I do? Is there a way to fix this? I know Apple sells "repair replacements" for the iPod Touch 4ht Gen. 32GB (the one I have) but I'd rather not spend $150 for a two-year-old device when a new and better one could be right around the corner, or if there are any cheaper ways of fixing it. Thanks SO much!!