The rods are dead centered and steady - so that is not the issue. Besides the design change, bearings could be used to keep the smooth glide.
Notwithstanding above, if we imagined the system at 90 degrees, there might be a few good ideas?
There are two sets of shims - here is the image of the first one. They are tilting to the right in the image... they need to slide up and down the rods perfectly horizontally... right now there are bushings/spacers. The shims may have to be redesigned such that they are thicker on the left to...
Horizontal shims that slide on vertical rods:
I have 10 long aluminum horizontal shims (nearly 8'') that have two identical holes (diameter nearly 0.5") on one end. Two vertical rods pass through each of these holes such that the 10 shims are stacked. These shims are required to be perfectly...