Hello Luke,
the rods of my printer-kit have been to long. If i would mounted them like it is described in the manual, mounting the black tabs would pull apart the body housing more than 1 mm on each side.
So i grindet and polished the front surfaces of every rod until caps fit in place without tolerance and applied some grease.
meantime i printed a lot, printer runs every day. (by the way: i like the printer a lot and want to say that it is the best you can get for the buck in my opinion, and it is a very good made kit, means with all pros and cons and do not want to talk bad allways ;-))
So after time the plastic-hemispheres in the tabs became flat and i got tolerance, means the rod can move (not only rotate)
I solved this with “Kugel-Rasten” we called it in German, i do not found this word in english, direct translation is “ball-notch” (don’t know whether this word makes sense ;-))
It is a headless screw (available in M3,4,5,6 …) having installed a ball on one end and a spring inside. i used M4 x 15mm long
You drill a hole in the center of one tap, cut a M4 thread in there (or use a M4-screw to cut the thread in a 3.5 mm hole) and then screw the ball-notch in with some grease and a nut over the ball-notch.
Now you have an adjustable ball-bearing, running for next 20 years without any tolerance and friction.
On the other side of the rod, once the tap is flat inside, you can add a single ball in an abatement drilled in the tab, hold in place with grease till mounted, or you do same like above with another ball-notch.