I Never said that the servo drives the gyro! As a newbie what it appeared to me was,the gyro was locking in HH before the servo finshed moveing the tail, which would make the tail come back to the HH position. As stated before ,the tail had vary little damage in the crash. The servo runs smooth with or with out the linkage hooked up or on anther channel. I did not remove the cover and look at the gears becouse it seemed fine. The 401 appears fine and is mounted well to the bottom of the heli. I fly this heli as is with out any other issues. The tail wag is consistent not sporadic ,so I belive the 401 is not damaged.