Mustang Electrics Problem

[JRC1]

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.
https://youtu.be/y4DrumYTspg
Thanks in advance for any advice you can offer to diagnosing the problem. is it the pick up selectors, the pick ups themselves?

[The Dude]

That could be a multitude of things. I'm thinking there is an open circuit somewhere- bad switch, open pickup, missing ground wire. Try thoroughly cleaning the pickup switches first with some contact cleaner. From there, it's just checking continuity with a meter. Check for open pickups. Check that the switches are switching. Check that everything is grounded as it should be. If you could upload some pictures, we may be able to spot something.