@EricNugent pointed out that the bearing mounts are prone to cracking between the layer lines on the rings that hold the bearings and that this might be a critical failure causing false positives on filament run out.
'Assembly using the bearing mount (PP-GP0418) and the bearing stack (Filament wheel + washers + m3 screw + bearings + magnetic wheel thing) is pretty difficult to assemble and really important that we get the stack tight and with the correct number of washers.
The solution I brought up to @tutley and @west was to make the bearing stacks beforehand, and design the mount to be a press in place or clamshell design. The problem is space in that area, not a lot of room for design, but that is the purpose of this ticket.
Everything else for the filament run-out sensor has been fairly easy to assemble in a batch until you get to installing the bearing stack.' - EN 12-5-18