Personally I would be leery of touching anything else but the calipers themselves. You could introduce more issues unrelated to the original issue.
It's been awhile since I put seals in my calipers but do they have to have a specific orientation? Some seals have a chamfered set in they're not exactly square and they need to be put in the cylinders correctly or they won't work/seal right. Only way to tell is to feel the seals in the cylinders and see if there's a lip and orient the new seals the same way.
I'm thinking if there is a right way, you should feel the lip on the top side of the seal.
My issue that lasted years was a shudder in the front brakes. I replaced everything, sometimes twice. One piston wasn't working right and once I replaced the seals everything was fine except I now have to replace the washer on the left side as I put two of them on the same side.
http://youtu.be/C26ww0dsMTI