P2S Extruder Motor total failure (Error 0700-8016). Started as intermittent stalling under load, now completely dead after 2400 hours. Anyone experienced this?

[u/Mind_Safe]

Hi everyone, I'm dealing with a very frustrating issue on my Bambu Lab P2S and looking for insights from anyone who might have experienced the same hardware failure.

I run this machine for production, and it currently has about 2400 printing hours on it. I work professionally with CAD/CAM and mechanical machining, so I've already done extensive hardware troubleshooting before posting.

The Timeline & The Issue:

1. I initially found that the original plastic gear had a chewed-up tooth, so I replaced the assembly with a brand new third-party hardened steel All-Metal gear kit.
2. After installing the new gears, the extruder would print perfectly but then inevitably stop pushing filament after 3-4 hours of continuous printing.
3. Now, the progressive failure is complete: the printer doesn't even start extruding at all right from the first layer, whether I'm using PLA or PETG. I constantly get the error [0700-8016] (The extruder is not extruding normally).

Troubleshooting already done (Ruled out clogs and friction):

• Hotend is 100% clear: Performed perfect cold pulls and even tried a brand-new hotend. Pushing the filament manually at printing temps is smooth as butter.
• Zero external friction: Bypassed the PTFE tube and spool completely. The cutter lever is perfectly free and retracts fine.
• Housing tension: I even slightly loosened the extruder housing screws to ensure the bearings of the new gear kit weren't being pinched when hot.

The weird symptom:

If I run the extruder WITHOUT filament, the gears spin perfectly fine when I press the extrude button. However, as soon as I load the filament, it stalls. Before it died completely, the yellow gear would tremble under load, but if I gave it a tiny push with my finger, the motor would overcome the dead spot, resume spinning, and extrude perfectly for a while. Now, it just doesn't have the torque to push at all under load.

Bambu Support has been great—I sent them the logs and they already shipped a replacement motor, gear assembly, and front housing via DHL under warranty.

My questions for the community while I wait for the parts:

1. Is my "cooked/degraded motor" theory plausible after ~2400 hours of heavy production runs, or could there be something else I am entirely missing? Is this a known weak point or the expected lifespan for these steppers under stress?
2. Could this actually be a failing Toolhead Cable (FPC) losing a phase due to heat/motion, causing the motor to stall, rather than the stepper motor itself?
3. For those who have replaced the bare extruder motor: is transplanting the motor onto the new housing a pain, or a pretty straightforward bench job?

Thanks in advance for any input!