I switched to a LIFE battery and bypassed the RX switch but to no avail. However I started to notice that with the bottom wing not attached to the fuselage ( ie just lying on the table below the fuselage the servo did not oscillate ) . However when the bottom wing was attached to the fuselage , the servo sometimes would oscillate . This was quite perplexing. I decided to replace the short but rather thin servo extension lead from the receiver to the wing with a thicker, twisted servo extension lead. The problem seems to have gone away . I will test it several times during the day tomorrow to verify. Can a thin short servo extension lead cause all this headache? Poor contact , rf interference ?? Strange.