The ESP Guitar Company

I recently bought a LTD - AT400 and I love the way it plays. But the guy put EMG-85's in the neck and bridge. I have a pair of Seymour Duncans that I like, so I swapped them out. The neck pickup sounds great, but the bridge has lost alot of power. It sounds very weak. I switched the volume pots for trouble shooting, but the problem still followed the pickup. Could it be a wiring issue or bad pickup? I've measured the DC resistance and it's good. How can you tell if a pickup is bad? Any advice would be extremely helpful.