QUBD : OneUp, TwoUp extruder spacer

I realized not so many people are happy with the default hotend (aka Anubis) of the QUBD OneUp/TwoUp printer, suffering from too frequent filament jam.

In my observation, the jam happens with 2 major reason.
1. The filament is not aligned with the drive gear.
2. The heat from the hotend also warm up the filament between the hotend and drive gear, which soften the filament. Once the filament is soften, it cannot be pushed straight but bent and jammed eventually.

The problem 1 and parti