Hangar 9 85cc Sukhoi SU-26MM Assembly Manual page 12

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Step 5
Attach the ball end to the servo horn using the hardware
provided with the ball end. The attachment point will be
1
1 / -inch (38mm) from the center of the servo horn.
2
Adjust the linkage to center the elevator. Remember
to keep the servo arm 90 degrees to the servo while
adjusting the length of the linkage.
12
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Step 6
Repeat Steps 1 through 5 for the remaining elevator servo
and linkage.