It appears that you covering could be reshrunk on the underside and pull it down. As it looks like a more like a warp. If not pull in on the linkage for that side a couple of turns on the clevis. If you havent noticed, my ailerons are tweaked like that and it flies perfectly level. Thats because the tail is 2 degrees canted. Not noticable but took some tuning to get rid of. Cya this weekend.