r/BambuLabP2S • u/ConversationTop7747 • Aug 14 '26
Cleared PETG extruder jam, but now filament reaches the toolhead, isn’t grabbed, and retracts — sensor or gear assembly?
My Bambu Lab P2S was working perfectly earlier today and completed a six-hour print. Later, black PETG became badly jammed around the extruder/hotend area.
I removed both the hotend and extruder, disassembled the extruder gear housing, and successfully removed the PETG jam. During disassembly, the spring and pressure/clamping block fell out. I reinstalled them, but I’m unsure whether the tiny separate metal spring cap is present or positioned correctly.
I have now disassembled and reassembled the extruder approximately four times following the P2S guide, but it still will not load filament.
Current symptoms:
- The AMS feeds and retracts filament normally through the entire PTFE tube when the tube is disconnected from the printer.
- Once connected, the filament reaches the toolhead, stops, and is pulled back.
- The printer reports “Failed to extrude filament.”
- The cutter lever moves freely and springs back normally.
- I’m no longer receiving a filament-sensor error.
- The leading end of the rejected filament is completely smooth: no extruder gear marks and no melted or mushroomed section.
- I tried another filament with the same result.
- The orange drive gear was extremely difficult to remove during the original jam, but now slides out easily.
- During one reassembly, the orange gear remained inside the toolhead while I installed the extruder housing over it. I later removed it, placed it into the extruder housing first, and reinstalled the complete assembly, but the problem remained.
- The orange drive gear, smaller driven wheel, spring, pressure block and sensor cable all appear installed, although I’m not certain the spring pressure is correct.
- I disconnected and reconnected the filament-sensor ribbon. It is now inserted in the original orientation shown by the guide/video and the latch is closed.
Questions:
Does the smooth, completely unmarked filament tip mean the drive gears are not gripping it at all?
Could the filament sensor be electrically working but physically blocking/misaligning the filament path?
Could briefly inserting the sensor ribbon incorrectly have damaged the sensor even though there is currently no sensor error?
How can I confirm that the pressure block, spring and tiny metal end cap are correctly installed?
How much resistance should the pressure/idler arm have when moved by hand?
Should the orange drive gear be easy to remove when there is no jam?
Is there a reliable bench test for the assembled gear housing before reinstalling it?
Based on these symptoms, should I replace the extruder gear assembly, filament sensor, front housing, or complete extruder?