hey guys I got a question about the diff

I so know I installed everything right, it all moves and works properly, but when I completely tighten down the diff case screws, it becomes hard to move the spur for 1/4 of its movement, when I loosen everything off it spins freely.

Is this just a matter of everything needing to break in and ill just have to keep an eye on it and tighten it up as I go?

Also the outdrives, they do move freely with resistance, but it almost feels like "sandy" resistance, again is that just a matter of things needing to break in? ie. the washers on the outdrives pressed against the ball bearings?

thanks! Ive never built one from scratch before, so I dont want ot make any wrong assumptions