You say they tail is stock, so I'm going to take it as you have not done anything in your radio or in the gyro to adjust tail gain. Which means when you power on your gyro, you should see the "A" light up for a few seconds, which is saying "No Gain".
Click the roller on your Tx and go down to Gyro. Set the Channel on Gear and I set my switch to D. I have mine programmed with +45 for position 0, 0 for position 1 and -45 for position 2. I do it this way so that I can flip that switch down to position 2, then back up to position 0 to center the tail blades before I take off.
You can set the Switch to On and just put in a gain value if you don't want to assign a switch to it.
But now, when you power up your gyro, you should see that the gain for the tail gyro shows somewhere around F or G and your status light should be Blue. If it is Purple, you are in Rate mode and you don't want to be there. You always want a Blue status light so you are in Heading Hold Mode.
