Prusa 4 not printing
My Prusa 4 intermittant not printing since November of 2025.
Tried updating to 4s. Replaced Heatsink, Replaced Planetary Gears. Run all calibration tests with no faults. Checked MMU3, checked screws on extruder. Updated to newest firmware.
Load filament to printhead using control panels, works most of the time. When printing from Prusa Connect, filament loads to extruder sensor and no furthur. Tension screws are 35mm with small 5mm adapter as per original build instructions and tightened so end of screw level with front of idler-nut. Tried without adapter and adjusted other settings. Printer still not working. Fault seemed to coincide with update in November.
Tried reinstalling Firmware update
When printer does start to print on the rare occasion when changing colour, filament stops at extruder sensor and fails to print.
Going to reprint idler assembly on Extruder
or am I overlooking something
RE: Prusa 4 not printing
And do you even have a sensor installed in the MMU version on the Nextruder? And if so, do you have this option set in the printer menu?
RE: Prusa 4 not printing
Sensors set set in control panel for extruder and MMU.
Did a cold pull. Had to use a lot of force to get filament through the extruder lever even when screws loosened off. Replaced extruder lever and nut but still the same. Planetary gears (New) don't seen to grab filament. Filament stops advancing as soon as it hits the brass nut with blue collar on extruder. Once filament gets passed extruder lever, printer works ok.
changing colour works but filament stops when entering extruder
Just checked setting on MMU, everything seems ok
Printer was working OK for 2 years. It's got to be something obvious
RE:
Going to try and print transucent gearbox cover to see if I can see where the problem lies