I am sorry you haven't had as good as an experience with your Zlin as I had with my Ultimate. Now I feel bad for talking it up so much. My covering was also wrinkled, but I just went over it with my iron, and it smoothed right out. Also, on my mini Edge, I had to put the battery pack in the aft fuselage section to balance it. With it there however, I didn't have to use any ballast. Your airplane is actually bigger than my Edge, and I have a Saito .30 in mine. I wonder why yours won't balance. I also removed the original motor box in mine and made a motor mount of my own. Good luck with the rest of it! Hopefully you can make it all work.