I had the exact same problem with my LT40. I replaced my hinges once with new ones and they failed the same way. I installed both sets correctly and I finally went to pinned hinges and they have not failed yet. I also talked to some of my Aerospace engineer buddies and they thought that the stabilizer might have been weaker then the elevator and flexing causing the hinges to shear. I tried to fix that problem by putting a hardwood stick across the back of the elevator. Don't know if it helped, but thought it couldn't hurt.