Thanks for the breadcrumb.
Had an online chat with them. Below is how they say they remediate the 5th gear issue as of May 31, 2023:
"When we build them we check the 5th gear to make sure it is tight on the shaft, if it is loose the gear is replaced and if the new gear is still loose the mainshaft is replaced. We use the nut that has 3 set screws with brass inserts under them.