[Kevin Sevcik]

I'd recommend stepping back, taking a deep breath, and then wandering off and working on more important parts of your robot. The small amount of backlash in that joint isn't going to make it meaningfully less sound, nor is it likely to affect any feedback code you have. The toughboxes are relatively inexpensive, but reliable transmissions. The small amount of slop there would be of concern if you were running at very high loads that you were rapidly reversing, but it won't be a problem for 99% of FRC teams. Any teams that would have problems with it would know that re-machining the shafts is your only option. "Roughing" up the shaft will only give you a false sense of accomplishing something. If you're running the kind of loads where the slop is a problem, a few puny dents from a center punch are either going to get flattened or going to gouge out the inside of the gear. Neither helps you out. If you're not running the kind of loads where slop is a problem, them you don't have anything to worry about anyways.

So, short answer, the slop isn't a problem, just a consequence of the low, low price of free that you got the trannies for. "Roughing" the surface won't get you any benefit and might actually be harmful.