P1S not pulling back AMS filament slot 4

Bambu Lab P1 Series Troubleshooting
1

When printing with 4 colors, the first 3 AMS slots run in and out as usual. Slot 4 will load just fine, but when it’s time for a color change, the toolhead does not always go all the way to the corner to cut the filament. I have pushed the cutter in to manually cut it, but it still just pulls and pulls without be able to remove the filament. So, I removed the PTFE tube at the toolhead and gave it a pull. It came out, but needed some force. I have been manually pulling that color back for too long now.

In the AMS itself, slot 4s light is red quite a bit, but it will turn white, sometimes, if I wiggle the filament up and down a bit.

All this being said, there is the odd time that slot 4 will unload just fine.

Not sure what or where to look. There is no filament stuck anywhere. The AMS has been pulled apart, cleaned out, new tubing. Scratching my head.

2

Is the led of slot 4 still on even without filament?

3

Look at the slot 4 rollers. Sometimes one of them is out of the correct place (compare with one of the other slots rolles position).
A simple push in should solve it.

4

Decided today, it’s got to be something in the toolhead. Took the nozzel off. Its a writeoff. Plastic pushed out all over the place. Was able to salvage the fan off of it. Put on a new hotend. Thought I was done. Not so. It was still not extruding. Pulled it all apart. The extruder gear assembly was in pretty rough shape. Changed it out for a hardened steel one and Bobs your uncle. It’s working perfectly fine now. I do not understand why it only affected the filament in slot 4, but its all good now.