RE: Exo Terra build questions and comments
Ive made that mistake with the differentials of an Emaxx. Its easy to do because there is no visual difference between up/down and left right.
As far as the O ring trivk is concerned, guys have been putting them in the axle cup to take out some slack. I havent done this to mine yet but I also havent got too wild with mine yet. I hear that it happens when you jump a lot. Alternatively you can upgrade to CVD axles.