Do I remember rightly that the skew-gear issue was found to be due to order-of-assembly?

As for gear tooth wear, this also brings up the old chestnut of cycloidal vs. involute teeth forms. In theory, the cycloidal form is subject to less sliding friction as the gear rotates, resulting in less wear. People will try to claim that this is the reason my 200-year-old Grandfather clock is still happily keeping time on the far side of the room. In reality, especially with modern manufacturing methods, it makes little difference. Wikipedia has a good illustration of pressure angles and contact points on involute gears

http://en.wikipedia.org/wiki/Involute_gear