There is no way that I can see to adjust the pre-load on the idler bearings. A very stout cap held with three bolts and instructions to just tighten the bolts. No mention of threadlocker or even lockwashers.
Any experience with this? There is plenty of meat on the cap so I could machine out either the center or outer part to change a few thousandths (or maybe several) in pre-load but don't have any clue on what rolling torque should be.