THANK YOU ALL FOR ALL THE RESPONSES. It took me a while to get back on this thread due to tax day among other things so thanks for your patience. Battery is 6V 1600mAH. The direction of KE right to left has the push rod in tension so it can't be buckling. I guess it could be stalling, I never thought of that, I thought I had it running full throttle, so a stall would be a surprise but I guess it is not out of the question. I will take it out this weekend and KE it the other direction (left to right) to see what happens and report back. I am thinking it could be a voltage drop so I will install my 2000mAH 6V battery to see if that changes anything. Yes, the rudder servo is brand new Futaba 3010 and when I put it under load on the ground the rudder, rod, clevis and servo all hold well.

Prop is 14X10 and the Rudder servo is mounted on the side of the fuse near the tail with about a 7 " long rod, whatever rod is the next larger than the 2-56 (there goes my memory again!) is the one I used, pretty heavy stuff and the control horns are all the heavy duty type. Radio is Spread Spectrum Futaba 8 channel