Hi - I have a problem with my Mustang. I thought it was just the input jack, however, I am not entirely sure if it is and before I start messing around with it too much I want to ask some advice and see if I was correct. Here is a link to a YouTube video which shows there's a hum when anything metal is touched on the guitar. There is some output when pickups are selected but it's not great. Thanks in advance for any advice you can offer to diagnosing the problem. is it the pick up selectors, the pick ups themselves?