Just as a follow-up on this. I took the elevator mechanism back out of the Hawk and replaced both clevises included in the kit with ball links. The only play at all before was the small amount of play where the clevis pin went through the hole in the stab mechanism control arm. That allowed for about 1/16th play in the leading and trailing edge of the elevator when installed. The ball links took all the play out and it is not held rigid. When I put it back in and powered up the servo, SHAZAM....the flutter was gone. I guess just that minute amount of play is enough to cause the 9351 to "hunt" for center and flutter. I asked Barry to look at the plane before I put the ball links in and he said that the small amount of play that was present in the elevator was not enough to cause in flight problems, or to be a concern, but I guess these servos are ultra sensitive to ANY play at all. Hope this helps someone else in the future who is dealing with these same servos!

Woody