Can’t get side cover on 833

Glad you got it working.
There is an instructional video on you tube that was for tech info to their mechanics in the late sixties. They describe tapping the cover around a bit with the bolts not quite tightened to get the best clearance for the reverse lockout. It is meant to just slide along it matching part with no drag but very close. Tap down a bit within the tolerance of the bolt holes to get a bit of drag, then back up just enough to slide freely. I found it doing a search on you tube for 833 assembly as I’m replacing synchronizers and bearings in mine.