RE: Servo extension & retract servo
If you disconnect each pushrod from the Servo Arm and then Push it and Pull it, does each retract go Up all the way, then Lock, and Down all the way, then Lock?
It could be that the pushrods move further one way than the other. if so, using the Servo Wheel, you can drill the holes for the pushrods so you get some differential.
Are you sure that the pushrods are strong enough and that they are not Flexing? The pushrod wire should be strong enough to move the retract linkages properly. If you take the Servo Arm or Servo Wheel off the servo and twist it by hand, you should be able to tell if the Retracts are moving Up and Down properly and you should be able to tell if the RT88 is strong enough to operate the Retracts properly.
When I used the RT88 servos on my H9 P47-150, there was one servo for each Retract Main. When the plane was upside down, the RT88 could not bring the gear to the Down position fighting against Gravity. I also had a plastic Gear strip in one servo. When I switched to the JR 791 Retract servo, they had plenty of Torque and Metal Gears, as well. My pushrods were only 1" long and Straight. I used 4-40 rod. If your pushrods are Bent or Curved, they may flex.