i had a bad wobble in my 68 after a hard landing. checked the blade balance,tracking, still there,with the main blades off the heli its hard to see any damage to the main shaft..I removed everything down to the swash so nothing is spinning with the main shaft but the washout base,spunup the moter and noticed a slight wobble in the main shaft(less than 1mm) that could not be seen with everything on the heli. Just a slight bend to the main shaft and everything wobbles