HZ was very nice and are sending me a new board - they suspect some 'foreign matter' got into the servo's drive mechanism...sounds logical and very likley however I can't see anything in there - even with a magnifying glass. Blowing it out won't get it out either.
I fired it up on the bench and worked the servos and motor. The rudder servo does stop working - whether it's a jam or a dead spot in the motor or something else I can't say.
I am sure my next model will be bigger with conventional servo/receiver/esc though - as i ran the motor and the servos it was noticeable that at high throttle the servos would hesitate a bit and on full throttle or low batt I could get the motor to stop completely requiring the throttle be set to sero and started over again. Not great for precision controled flying or IMO, learning...'what did I do wrong?' moments may be the plane's fault.
I was thinking of a um warbird but may need to go bigger to get conventional electronics, and that may be more 'bird' than I"m ready for...rethink time.