I came across an issue when installing my control column and thought I'd share it as I haven't seen, via a search of this site, that anyone else has documented this problem.
I noticed an excessive force was required to move the control stick fore and aft after installing it in the frame. The problem turned out to be the outside end of the bushing welded in the right end of the control column - the surface wasn't flat and not normal to the axis of rotation. The solution was a jig set up to ensure a little (or, a lot) of filing didn't make the situation worse.
The picture shows that situation about half way through the filing process. A few more details and pictures can be seen on my build log.