I have one here in the UK flies OK but needed a handful of down elevator when inverted I did all the usual checks c of g wing incidence and tried again but no better I have just found that the tailplane has a warp near the end about 4 inches fron the end so I have taken it out and I'm replaceing it with a solid one I did read where someone had very bad tail flutter which shook the elevator hinges apart so it may be a weak point I also replaced the elevtor push rod with a through the fuse crank type lot better. Albert