Have you tried tightening them? I was noticing a small amount of drift in my v2 and just tightened it a little and it feels a lot better.

Only issue I've got now is one I've had on a lot of xbox controllers which is the left bumper not registering all the time. I think it's because of where I press on the bumper it eventually causes it to break over time, I actually replaced the bumpers on my old core controller once and it had indeed broken at the spot where it presses down onto the button on the mb.