Symptom: The printer stops because filament will not feed from the AMS Lite.
Problem: The PTFE Bowden Tube is detaching from the AMS Lite.
Cause: A crack in the small plastic retainer ring at the top of the AMS Filament Funnel Unit is causing the Bowden Tube to detach when pressure is applied.
Fix: Print this compression ring. It has a tapered hole. The print bed side goes down against the AMS Lite unit. Press the ring in place around the cracked part and the problem is temporarily repaired.
I have had two of these fail on me in the last year. Both times the part was under warranty and Bambu was quick to send a replacement. But I can tell you it is not an easy part to replace. It requires you to replace all of the guts inside the filament funnel. And to reassemble it you must have the gears and levers in a specific position and blindly replace a spring that is under tension. The instructions were for a mirror image filament funnel (there is a right and a left design that are opposite of each other). It took me two or three attempts to get it back together. This repair part simply adds some reinforcement to the fragile plastic part where the PTFE tube connects. I am not sure how long the fix will last, but it is much faster and easier than disassembling and reassembling the AMS Lite.