It would be great if the roller holder were a bit more robust, or if it were possible to purchase one that is more robust.
The way the roller-holder is currently designed, a very small amount of contamination will result in the roller-holder effectively being destroyed before you have the opportunity to discover there is a problem.
The little v-shaped “nubs” that make contact with the rollers on the top, these appear to be the culprits. My impression is a small amount of resin on the rollers results in friction with the nubs, heating-up the nubs, after which they get worn-down. As the nubs flatten, it results in more friction, eventually causing a vibration to develop as the LPU moves along the rollers. The rollers begin to bind and you get vibration that eventually causes print failures.
Ideally there would be a way to either pre-emptively discover the resin contamination so that you could clean the roller-holder before damage is done, or there would be some way to rebuild the roller-holder after the damage has been done, i.e. have something like replaceable “nubs”.
Perhaps the design can’t be improved significantly. I certainly have to get better at avoiding resin contamination.