Try wrapping a dry warm small towel around the hood. The heat from the towel will cause the hood to expand slightly and it should be a little looser. Make sure you don't heat up the lens. After a few minutes, try to turn it with out pushing it toward the lens, instead pull it gently away from the lens while turning it.You can keep it warm using a hairdryer but on a low setting the hood might warp if to much heat applied GOOD LUCK,