Do all vintage mutoh drafting machine suck?

As an owner of 3 (2x MODEL S, 1X Model L) they all have the very same annoying problem, the bearing produce a very clear "thumping" sound while moving the head up and down.

I have tried everything from using masking tape to changing to polyurethane coated bearing from the regular aluminium ones but they all do it even when there is not a scratch on any bearing, it's like either the internal shafts of the adjustable rods are either bent slightly or the whole profile has been worn out despite looking fine.

Has anyone else encountered this issue?, the main arm has a larger rubber bearing but all the rest are plastic, it moves fine, very hard to feel anything but this head is just a disaster.

All of my Mutoh machines are like that, is that the normality with all parallel motion machines? I'm a user of an arm machine that I never had any problems with, my friend too has a Bieffe machine that is mounted on a large chromed rod with rubber wheels on each side and that works absolutely amazing.