The P1S has two common feed paths: the rear spool holder and the optional AMS. Pick one path and make sure the PTFE routing matches it before feeding material.
For a rear spool, cut a fresh angled tip, guide the filament into the PTFE tube and push until it reaches the extruder. Use the screen controls to heat the nozzle and extrude. The official quick-start procedure asks you to continue until filament exits the nozzle and cannot be pulled back by hand at the PTFE anchor.
For AMS loading, place the spool in a compatible bay, check that it rolls freely and feed the tip into the inlet until the first-stage feeder captures it. Enter the material and color in the AMS panel. A wrong material mapping can send PLA temperatures to PETG or the reverse.
Use the Unload command instead of yanking filament from the cold extruder. Let the printer retract it, then rewind the spool while keeping light tension. Secure the end immediately.
Some flexible, brittle or abrasive filaments are unsuitable for a particular AMS configuration. Check Bambu’s current compatibility list and use the external path when instructed. If a spool resists feeding, inspect its winding, diameter and PTFE bends before blaming the extruder.
Longer-term spool care belongs in the broader filament storage guide, especially once several materials are cycling through the AMS. If the AMS bays themselves still need wiring or desiccant, the P1S AMS setup guide covers that groundwork, and matching the loaded material to a saved profile is covered in the Bambu Studio profile setup for the P1S.