What's going on with the electronics/pickups?

[Chas Krijnen]

Dear Ken Smither's,

In 2012 I bought a new Ken Smith Quilted Maple 5EG. It's beautiful looking and sounding bass. But a little time ago I have some trouble with it.
I have setup the bass and pickups myself when I first got it. I screwed (up and down) the soapbar poles one time, but found it had no huge sound improvement, so I screwed it (factory default) all back to flat in the pickup.

First of all, I'm very respectful and gentle with all of my instruments, so this problem came all at once. The problem occurred all the sudden. Since a short time it happens often when the bass isn't plugged in for a while. And only occurs on the front pickup when I toggle the series/paralel switch. I did change the batteries, but found no cure. There are also no lose wires or joints in the electronics cavity.

I found a work-around the problem... when I slap against the front pickup, it will work again... You may know that it isn't the cure, so please help!

I made a little clip of it with my phone

https://www.youtube.com/watch?v=QMT_...w&spfreload=10

again, please help!