Install 2 608 Bearings with the M8 x 35 BHCS, M8 washers and M8 Nyloc nut.
Tighten Bolt all the way down.
Note, there is no washer under the head of the bolt.
Assemble the double bearing holder onto the x end idler with 4x M3 x 12 SHCS and washers.
Leave the bearing holder loose at this point.