Pay careful attention to the orientation of the Main Shaft Bearing Blocks. It is important that the side with with the lips point away from the assembly. The lips hold the bearings in place.

There have been reports of crown gear teeth stripping in the air, i.e. not from the tail blades hitting the ground. If the Main Shaft Shim (106-120) is not installed and there is ANY play between the bevel gear and crown gear the crown gear will strip in fight. It is recommended to install the shim and position the bevel gear/boom correctly (page A27) and let the crown gear break-in during the first few flights. The position of the bevel gear forward or toward the rear will set the tension of the bevel gear on the crown gear. You want some medium tension but the trick is to have no endplay or overly tight mesh. The shim as well position of the bevel gear will give the user some adjustability. Also, you always want the Transmission Output Assembly fully inserted into the boom when ever adjusting the bevel gear

Make sure you do not over tighten any of the hex bolts that secure the main gear or crown gear to their respective hubs. Doing so will potentially strip the aluminum bolt hole or warp/crack the gear.