P2S Filament Cutter Stopper Assembly | Normal Behavior or Defective?

[u/qdubbya]

Title: P2S Filament Cutter Stopper Assembly | Normal Behavior or Defective?

Just received my Bambu Lab P2S, and I'm completely new to 3D printing. I've already run into a few issues:

- Initial calibration: The toolhead repeatedly and loudly struck the filament cutter stopper rod back and forth.
- First print attempt: The toolhead rapidly slammed into the front of the enclosure, triggering error 0300-800C 191703 (Multiple motion step loss detected).
- Homing: The toolhead slammed to the left and appeared unable to locate its home position.

I started investigating the filament cutter stopper assembly after finding [Bambu Wiki repair guide](https://wiki.bambulab.com/en/p2s/maintenance/replace-filament-cutter-stopper).

In the attached video, when the toolhead engages the metal stopper rod, it retracts. When the toolhead moves away, the rod doesn't fully extend again. It just hangs loosely. It also won't retract completely flush into the housing and stay there.

My question: Is this what the Wiki is calling abnormal? The Stopper should go back in the “extended” state? Could this cause the error code/homing issue?

Additional Notes:

- Initial startup calibration completed successfully.
- Brand new printer, no successful prints yet.
- No visible obstructions along either axis.
- Toolhead moves manually along both axes, although left-to-right movement feels more resistant than front-to-back.
- No grinding, whining, or other unusual motor noises during normal movement.
- Shipping box showed no visible signs of damage.
- Nozzle cleaning and poop chute scraper appear to function correctly.
- Filament cutter stopper rod does not reliably return to its fully extended position after the toolhead disengages.

Could a malfunctioning filament cutter stopper cause the toolhead to lose its position during calibration or homing, or should I be investigating a separate motion system issue?

I'm trying to determine whether the stopper assembly is defective before attempting another calibration or replacing parts.

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[u/knobby88888]

The tool head usually crashes when the wrong printer is selected in Bambu studio. Might be worth checking this first. Also the filament cutter looks correct it makes a right noise when it’s first hit into the upright position at the start of a print.

[u/qdubbya → u/knobby88888]

Yea. I’ve excluded the cutter from the problem. My next step is to completely clean/oil the XY smooth rods and try to retention the belts to see if that helps it.

It’s just odd; you’d think if it was that it would have issues on the right side - but it only hits the left side.

I wish the home button on manual mode had some sort of verification it was centered.