MMU fail
Waiting for support chat, putting the video here. Any community input is of course appreciated.
- Symptoms: The MMU fails to initialize, doesn't move any motors at power-on and gives blink code (video)
- I cannot make sense of the blink codes with the knowledge base article (and even so, it doesn't offer solutions)
- It failed during a print that used only a single spool. The filament got stuck at the spool and snapped (by the Nextruder motor, as the MMU is disengaged during print).
- The failed print gave the message on the display appeared: "FINDA" error
- There are no other error messages given by the firmware (using latest RC2, reverted to last stable but no change)
- Prior to the failure, it ran like clockwork.
Other than the elongated filament, there is no sign of mechanical struggle with the MMU (e.g. no debris on the MMU pulleys).
There may be a faint Phosphorus note in the air ("magic smoke" smell of burnt electronics) but I can pinpoint it to neither MMU board nor main board.
The video is here, my browser doesn't show it: https://storage.googleapis.com/prusa3d-content-prod-14e8-wordpress-forum-prod/2025/11/af70faab-mmufail.mp4
RE: MMU fail
"Best answer" goes to Ruben from support. The first question asked was bull's eye: FINDA LED.
There was a piece of stuck filament in the FINDA, I had to insert filament "in reverse" flush with the PTFE tube, then move the slider, then push it out (short of disassembly).
The LED should have been on but was not. MMU brought back to life. Case closed.