last bit for now:
after the above machining, i have my pan axis truly plumb when the pan platform is truly level for the full 360 degree rotation.
the second thing that really matters is (how) to determine the mounted camera is also level when the pan platform is level. I am using the Cambo WRS, which has bubble levels for both ways mounted on the top of the body. here is what i found:
to determine if the body itself was plumb: done by aiming a self leveling laser at the lens mounted on the Cambo: laser height set so beam hits center of lens; then a clear glass cover plate was fitted over the lens barrel, which reflected the beam back to the source; it was within 1/4" of being on the source over 14', i can live with that. (I am only setting forward/back level)
however with the pan platform truly level, the cambo mounted using a RRS base plate, the front-to-back reading on the Cambo level was considerably out; the edge of the bubble was all the way at one of the lines. So even if you are not panning, using that to set level will be incorrect. the solution will be to re-fit the cambo level.
the horizon and the grid function of the IQ can be used to check the left/right level.
what I am going to achieve is to have both the cube and cambo levels consistent and accurate for level, both ways.
all this time i have been leveling with the cambo levels and they are off. for example, if using the laser setup, I set the cambo bubble to level, the reflected dot is 2-1/2" high. (or if i set the cube bubble to level, it is 1-1/2" low.)
over 14', 1" out is about .4 degrees, but since it is reflecting the dot it is half that angle or say 1/4 degree per inch of dot mis-alignment. the cambo level is then out by a bit more than 1/2 degree.