This isn't meant to replace the instructions
Once you are familiar with the gyro, reread the instructions and check here.
First plug the rudder servo directly into the rudder channel in the receiver. Check the direction. Right rudder should pull the control rod to the front of the machine on most brands. Verify this by standing behind the model and watch the tail blades as you give it right rudder. The leading edge of the tail blades should move left.
Remove all subtrim, stunt trim , revolution mix and any other mix that involves the rudder channel. Center the trim tab on the rudder. For the CSM gyros a fairly long arm seems to work better. You can start at 15mm. Fit it so the arm is about 90 degrees to the rudder control rod. Adjust the length of the rod so the t/r bellcrank is 90 degrees to the rod. This might not be perfect, but it'll get you going.
Turn off the power to the model. Now go ahead and plug the aux-in into channel 5. Channel 7 has some issues that complicate things and we're trying to keep this simple. Futaba guys need to inhibit the gyro function
Set the ATV on channel 5 to 60% on both sides. Set the ATV on channel 4 to 90% on both sides.
Adjust the gain pot to about 50%.. Turn the model back on.
Check the direction of the gyro. You know that right rudder pulls the rod forward. Yaw the machine to the left and watch the rod. If it moves forward you're in good shape. If not, either remove or replace the reversing jumper.
Move the rudder to one side and let go. In heading hold, the slider should stay in place or drift slowly back to center. In normal mode it will return to center immediately. Put it in heading hold. Now adjust the subtrim on the rudder until the rudder stays put and doesn't drift. If your transmitter allows it, cut the trim rates to 50% to allow for finer adjustments.
Now go hover the model. It will want to swing rather violently as it get light on the skids and before the tail blades gain the authority to control yaw. You'll anticipate this after a few times and it won't be a problem.
If the tail wags in a hover, lower the gain a couple points and try again. If it doesn't wag, raise the gain a couple points until it does, then back off a couple points.
Go ahead and use the trim on the rudder, but when you get it trimmed, you'll want to transfer that to subtrim so it will be right in all modes.
If the gyro doesn't work at this point, it's broke and needs to be serviced.