AMS fixes - failed to pull filament

I just purchased a second AMS to add more colors, it’s on it’s way. I have had a few prints fail on AMS slot 3 and I’ve seen a few fixes, my questions are:

  1. Is there one “fix” that most have landed on as the way to go?
  2. Can the mod be undone?

I wouldn’t want to damage my units in any way, just I wanted to clarify before proceeding.

I had the some times the failure, that the filament was unable to retract.
I found this and installed it:
AMS Fix Failed To Pull Back Filament Error
I had recently a print with 200 filament changes and no error.
The guy has several fixes and none are permanent. Try it.

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My collectiin regarding this

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You can check out my profile for ams related fixes. It is not a one fix cure all, may work for some but don’t for others but its possibility the best fix avalaible currently. 3 of them are in top 10 trending. Most of them past 1k some nearing 4k downloads.

Quite a lot of positive feedback but do please please view the installation video of the fixes carefully. Thank you.

Just search for SPStudio user or go to trending top 10 there are 3 there.

There are potentially many reasons for an AMS retraction issue including which AMS revision you received.

My original AMS had a lot of issues retracting.

After I installed these AMS button covers along with a small piece of PTFE tubing it smoothed out the filament bend angle to the 1st stage feeders and solved the majority of my issues.

In some cases it can be due to you are getting down to the end of a spool and the spool gets to be too light (installing desiccant 'spindles’ or just even C/D batteries in the center hole of the roll can fix that cause).

Some cases it is the bend angle of the PTFE tube going into the print head itself, installing a PTFE Guide can help.

As others have called out it can be due to the angle you have your PTFE tubing routing into/out of the AMS buffer/Hub.

And sometimes it is just gremlins and things smooth out after the printer is ‘broken in’.


Ther always is not ONE solution. Every Setup ist similar but not the same.

You have to try what fits YOUR Problem. Trail and Error.

that is why i have the complete range of fixes to solve this problem.

Trust me when I say, this causes it more than you think! Adding one of @PaulT solutions to this fixed a lot of these errors for me.

Thanks @tvirelli for the kinds words. Now that I have about a year of printing under my belt, very seldom do I get AMS retraction issues anymore.

The biggest headache I see now is the occasional brittle filament breaking off in the AMS Hub path where I have to pull the hub off to remove the broken piece.