Originally Posted by PaulB
old problem ( I think). You have to loosten the collet that holds the main shaft in place (above the top bearing) before you fit the main gear and then the gear pretty much must fit.
On most helis that would be true. However the 500's have a stepped area at the bottom of the shaft that the autorotate bearing seats against. That top collar has zero affect on the binding issue I was having in the gear area. After fighting it I assembled the shaft and gears outside the frame. I even tried a brand new Align mainshaft with the same result. That's how I was able to determine what really needed attention. Sanding the spacer was the only way I was able to achieve the clearance needed. Good thing I never leave home without my digital calipers.