Equipment fails. You fly long enough and its going to happen. I had a JR 537 fail on the elevator of one of my planes. Is a jr537 a bad servo, I doubt it, just bad luck. Get over it and move on or you will be out of the hobby in a short period of time. Most electronics fail very quickly after you start using it, if thier going to fail. Some guys burn in their equipment before using it. Dual elevator servos may have helped, You may want to look into a more redundant setup in the future.