MMU Needs Attention

How to Fix It

1. Look at the LCD for the specific message.

   MMU error messages on the printer screen tell you exactly which filament position has the problem and which move failed.
   Read the message carefully before pressing anything.
   Is it loading filament 3?
   Unloading filament 1?
   The fix depends on the specific situation.

2. Cut the filament tip cleanly.

   If the issue is loading or unloading, the filament tip is often the culprit.
   Remove the filament from the MMU, snip the tip with side cutters at a 45-degree angle, and feed it back in.
   A clean angled tip slides through the PTFE; a mushroomed tip jams every time.

3. Check the spool for tangles.

   Slowly rotate each affected spool by hand.
   Does it turn freely, or does it bind?
   Tangles inside the spool look like a single strand crossed over earlier wraps.
   Pull a few meters off, untangle, and rewind onto the spool tightly.

4. Inspect the buffer (MMU2S).

   On MMU2S setups, the cardboard buffer holds filament loops between the MMU and the printer.
   If a piece has snapped off and lodged in there, the next load won't pass through.
   Open the buffer, fish out any debris, and reset the loops cleanly.

5. Press the middle button to retry.

   After fixing whatever was wrong, press the middle button on the MMU to retry the failed move.
   The MMU will attempt the same move again.
   If it succeeds, the print continues automatically.
   If it fails again, repeat the diagnosis with whatever happens this time.