I am having a trouble printing. I had a problem with the extruder having a clog. I did a cold pull.
Now, when I try to print, the filament stops moving in the plastic (PTFE?) tube about 12 " from the extruder. The AMS keeps pulling it back and trying again. I disconnected the tube and manually pushed filament in it to see it anything would block it. It passed that point with no problem.
I dont see any damage to the tube anywhere.
The blockage occurs of the right side of the tube of the extruder.
I get “Unable to feed filament into the extruder. Could be entanglement or stuck spool.”
If I push the the filament through manually it will move. The AMS doesnt appear to gave any issues.
Check the PTFE ends (AMS to printer) for wear and correct seating. Make sure the ends are flush and pushed in fully. Also have a look at the filament end and recut.
Also, check if you can shorten/straighten the PTFE patch from the AMS to the printer. That not only reduces friction but also slightly reduces filament change times which is nice when having a lot of filament changes.
Is it a P1S? I ran into this exact situation before. I had this problem right out of the box. Every time, I had to manually straighten the connection between the PTFE tube and the extruder.
In the end, I discovered it was because the PTFE tube wasn’t fully inserted into the extruder. After I pushed it in a bit harder, everything went back to normal. It was a factory defect.
You can try removing the top glass first to see if the AMS feeds properly after that.
For troubleshooting, I suggest to feed some filament from the rear spoolmby hand. Watch carefully how far it gets into the print head! It can help to have the front print head cover off to the side to improve visibility. Where does the “hit” occur?
At the end of the PTFE tube? Even a tiny gap can stop the filament tip. You may need to recut the tube end at as close to 90° as possible. You can print a tube cutter or cutter guide from MakerWorld using the rear spool holder.
Does the PTFE coupler grip the tube well? Is it seated well? A spare coupler can be taken from the other end of the same PTFE. Replacements can be bought in the form of the 3-pack ptfe-couplers from Bambu. Each coupler contains 2 which need to be broken out.
Does it go past the PTFE end and stops at the end of the filament sensor? Is the sensor still firmly fixed?
Does it go into the extruder? Try to extrude some material using the display.
Ive been struggling with the same issue. The filament would stop at the hot end and then retreat back. Mine seems to “hit” the gears area and then retreat but I did straighten out the tube and cut the end to make it more flat. Did you find out what was causing the Issue on yours @Shrike ? Also if there are any other suggestions I would greatly appreciate it! Thank you.
I just fixed the same problem on mine. I replaced every part on the extruder and the filament still wouldn’t load. I finally took the filament hub off and there was a magnet stuck to the case. I pulled the hub apart and found where the magnet belong. I put it back together and the filament now loads without issue.
I’m glad you were able to find out was causing the problem. I found out for mine that I needed to replace the AMS internal hub unit, but I appreciate your feed back!
& 
Just a little more…