My dear PX 200 II's plug has shorted out. One of the channels is not getting sound, and the other one is cutting out. I know the problem is at the plug, since I've fidgeted with it a bit and noticed changes in the sound when I did. They are just old enough for the warranty to be void, and the rest of them are in pristine shape. I called an audio repair shop in my town, it would cost $40-50 to get it fixed. I don't know how to do it myself. Any ideas? I don't want to buy new ones.