Re: Wiring issue,....
Could also be the switch's contact plates are bent. Depending on the switch design, the inner plates touch to make contact and therefore you get sound. On others, you get sound when those plates are not touching.
In the center position, the plates on both sides will either be touching or not touching. Figure out which one you have and take a pencil eraser and gently push the contact plates toward or away from each other (whichever you got) and see if anything changes.
However, it's most likely what edwhuld said - stray hot wire on the jack connection.