What's wrong with my Ps3's controller analog?

I bought a new ds3 sixaxis a few weeks ago and at first it was obvious I needed to break in the analogs, and the left one did break in. But the right one is still pretty hard to move to the upper right, It can move perfectly around in circles but when I try to move it diagonally it requires me to use my thumb muscle to do it. Which makes it very hard to play first shooter games since instead of being able to move it fluently it jerks passed where I want to aim it at. Is there anyway to fix this? I've already cleaned around the analog ect but I haven't taken it apart yet. I'm thinking It's because of the spring in the analog is tight so I need to keep pressing it in to make it loose, but I'm not sure. Thanks