Epi T-bird with SSB-4 Bridge and Standard Neck Pup - HELP!!!

Hi guys.

Great forum! I've learnt more in the past hour than in the past 5 years just reading some threads on here! However, I've got (what I think to be) a really bizarre problem, which I've not come across in anything I've read as yet...

If this has been asked before, I'm really sorry!

I've got an Epi T-bird, all standard - well it was all standard until a problem with the bridge pup meant I had to change out the original - nothing whatsoever to do with the tone I must add - I've been really happy with the original pups sound.

I digress - I went for a Seymour Duncan SSB-4 as the replacement - fitted it all fine no problems. Now here's where it gets a bit odd.

With the neck (orignal) pup on alone, the sound is fine - and with the new bridge pup on, it's a little quieter (which is also fine - presumably the impedance etc is different)...

However, when both pups are on full, the sound seems a bit thin (thinner than it was with both the originals on together), and turning the bridge pot down a little ( down to 8 rather than 10) makes the neck come through much louder, and deeper... If the bridge is on full, turning the neck from 0 up to 8 makes no difference whatsoever, the sound is exactly the same, until it gets above 8, then you can hear it, albeit not very loudly!

I've rewired them to every combination I could think of, and nothing seems to solve the problem.

As a final thought, I'd just put a magnet across them both - turns out the original has a North pole facing up, but the new SSB's North pole faces down... Could this be my issue?

(or should I just have bought a pair of SSB-4's!)

Any thoughts or solutions would be VERY gratefully received!

Thanks a lot - and keep up the good work

Ben