Hydra pro self-centering rear rollers

Humebeam's Hydra PRO mod for the Bambu Lab AMS is a great design. However, I did occasionally run into an issue where a spool would walk left and right. So I remixed the rear rollers so they are now tapered towards the middle, which makes the spool self-centering and negates the need for the roller guides and outer edge. It also means you can use as wide or narrow a spool as you want and they will always run true. Fitment is the same as the original version, push in the bearings and then use M3 cap head bolts of a suitable length to act as the mounts.