Problem with my neck pick up

Hello,

I have a problem with the neck pickup on my Epi SG and I’m after advice before I try and  botch it.  I rarely use it as the bridge pickup is so much better for what I play but I started experimenting with both pickups a few weeks ago looking for contrasting sounds and volumes. 

The problem is that if I switch from the bridge p/u to the neck directly it sounds like there’s a loose connection and the sound drifts in and out intermittently?  If I then switch to the middle position and play both p/u and then back to the neck it’s fine (well usually)?.  Well I’m saying its fine but the sound still seems too muffled and way too bassey (more than a normal neck p/u on any other guitar I’ve played) which makes me think perhaps it’s the p/u and not a connection?

Any ideas or things to look for before I strip it?   

Another thing I noticed is that the distance of the neck p/u is about 5mm further away from the strings than the neck p/u but I’m not sure what the spacings should be, anyone know?

Cheers