I have had some retraction issues with spools that have very little filament left on them. I believe this occurs because the angle that the filament is entering the AMS is to sharp and it causes the spool to be pulled forward and loses contact with the drive wheel. I have seem some solutions that use a stand connected to the AMS entry buttons that the filament must pass over but my tests always resulted in filament flipping off the sides and getting jammed.

My solution was to create an AMS button that is held on securely and incorporates a TPU riser that makes the entry to the AMS feeder less extreme. As the filament is pulled in the button riser will flex slightly which reduces the pressure on the small clips that hold the button in place, making it less likely that it will be detached. I have tested on my old AMS unit with the small, low profile feeder buttons as well as on a newer unit with a taller feeder. I have NOT tested with any other modifications such as the Hydra mods.

Assembly

The button is printed in 3 parts. The primary section is the portion that attaches to the AMS feeder. The TPU riser is inserted from the bottom and up through the hole. The small funnel cap is placed on top. The TPU riser has enough clearance for a piece of PTFE through the body, I am using this to reduce wear on the TPU as abrasive filaments could chew it away.

Installation

The button is installed by slding the AMS feeder button forward and securing the back tab of the AMS helper button first. Then rock the helper button forward until the front tab clicks over the lip of the AMS feeder funnel. Usually I hear an audible click when this occurs. I then wiggle it a bit to ensure that both tabs are holding.