What Can Be Done to Fix My Keyboard?

I recently had my A1285, Mid-2012 15" MBP keyboard begin to act up. I would have to mash keys several times to get things to type. I figured that perhaps crud and whatnot mandated a replacement. I ordered a new keyboard and replaced the old one, only to find it doing the same thing. I would have to mash on the keys several times to get something to work. I figured I got a bad keyboard so I requested a new one and swapped out the keyboard yet again. Same problem. I'm at a loss as to what to do to fix it. I've tried resetting the PRAM and SMC, nothing fixes it. I'm able to use an external keyboard, but that really defeats the purpose of a mobile computer. Can anyone offer any further ideas/insights/repairs to perhaps tackle next?