Weird Extruder not extruding issue

I have an Bambu Lab A1 with AMS Lite. My printer has been working fine with both PLA and PETG since I bought it about four months ago. I have put quite a few hours on it…Probably over 2000 hours so far. I have started getting extruder not extruding properly messages. I have also started getting failed prints where the extruder just does not seem to be putting any filament out. I have run full calibration checks and it does fine doing dynamic flow checks. Then when printing job starts, the extruder just does not put any filament out and I get like a ghost of filament on my print plate. Does this off and on with both PLA and PETG that are properly dried.

To date, I have tried changing nozzles, both generic and OEM Bambu lab 0.4mm nozzles. I wondered if I had worn out the extruder so I ordered a new Extruder assembly and replaced it today. The new extruder also does not extrude after starting print job. AMS seems to be working fine. The extruder loads and unloads filament with no issues. Using the same filament that has been failing to extrude, I put it in a different AMS location. At the moment it is printing a Benchy with no issues. Could the AMS not be feeding properly and that is causing the extruding issues? I don’t know of any other cause that I have not tried to triage. I don’t understand why the dynamic flow checks would be good and then the extruder fails when doing a print job. Any advice or insight would be appreciated.

Update to above, I did reseat all my PTFE tubes and made sure they are not to bent. I was going to print out the tube guides to put on top of extruder housing as well as the guides for the AMS but cannot get printer to extrude at all during the print…still does the dynamic flow test fine.

Can you run an external spool successfully?

Have not tried yet. It is getting late here and that is on list for tomorrow.

Tried with single external spool of filament. Same issue…Gonna try replacing the filament sensor base…

Well, found the issue in a obscure post. Anyone else having this issue lookup the Bambu A1 Seven Screw issue. I followed that lead and pulled the hot end off and indeed, the 4 little screws behind the three screws were loose. Tightened those and I’m good to go.