Check Van's website. They have a list of things to check for a heavy wing. A list in order of things to do before you squeeze the trailing edge. I have not done this so I am no help.
Search for a thread on this site that discusses using a coffee-stirring straw taped to the trailing edge bottom of the right aileron to correct for a heavy left wing. I tried it to correct what sounds very much like your situation in my RV-8, and it worked perfectly the first try.