I had a wing balance problem with my avistar afr that i built last year. Apparently the winter had miraclly made the right wing heavier than the left. I pondered for a moment. After my head began to ache thinking of a solution, one hit me. I drilled a bout a 1/4 inch hole in the plastic tip, shoved 2 rubber bands into it.( this forced a perfect balance.) Then, I cut a small piece of white trim covering from an old sheet and slapped that over the hole. Went flying 30 minutes later at my high school about 5 mins away and had 2 excellent flights before darkness fell. This worked well for me, maybe you should try it?