Phil, Thanks for your reply but I think that I have now solved the problem. Both of the models being used to diagnose my yaw snag were fitted with FR-SKY TFR-6 Futaba compatible rx's. I replaced one with a genuine Futaba rx and all is now well. It would appear that although I have never had any problems with the TFR-6 before that it is not compatible with the Orange stabilizer in the yaw mode.