I dont think it is a quality issue, I think the issue is just like a midboard working or failing, or a Ring a and pinion issue,
Personally I like getting my own bearings from Timken Direct Supplier, On my S4D i get bearings with matching Races,
The other issue i see is the Crush Washer, I think the issue is the Crush Washer is not working correctly, its to loose or to tight, sounds like it might be to tight on the bearings, and causing no lubrication on the fulcrums,
I would want to feel the preload of a assembled bearings and compare that to a build your own kit,