[Cecil]

I'm not quite sure how to explain this.. but here goes..

Look in one of the gearboxes that don't sound right. On the gears inside the box, you will notice a small raised "flange" on one side of the gear right around the center. That little flange needs to go towards the case of the gearbox to keep it spaced away from the sides. When it is done right, all those flanges should be sitting right against the bearings in the case.

I'm sorry, I don't know of a better way to explain, and I don't have pictures to show you..