Malcolm,
I saw that they were very specific about not using ball and socket type of connectors. They didn't actually mention the ball-race connectors. The ball-race connectors fit very closely to the side of the horn.

Currently I am trying a servo-arm clevice on both ends. I am using a ny-loc 2-mm nut to hold the pivot point pretty ridgid. I put a ball and socket clevice on a horn as a test and the horn could be seen to flex when put under load. I could not get the same result with the ball-race clevice.

There is a way to be absolutely sure and that is to put two horns side-by-side with the ball-race bolted between them.


Regards,

Eric.

P.S. I'll try the tip about using the nylon ouput shaft to the servo arm. I had been a bit lazy and was only changing the middle gears.