A very dry or old filament can quickly become very brittle. Using brittle filaments in the AMS can generate problems during use as they can break inside the filament path.
This Bambu Lab wiki page is for when the filament has broken into the PTFE tube and needs to be removed.
As there are many different PTFE tubes between the extruder and the AMS path, the videos below describe how to remove these PTFE tubes, and if need be how to replace them.
If a broken filament piece is not easily falling out and is stuck inside the PTFE tube, you can insert a new longer filament piece on one end, to help push the broken piece toward the other end.
Please note that the PTFE tubes are consumables and are at risk of wear, as they may rub against the filament over time. We recommend that you check the PTFE tubes for wear during your maintenance of the machine. If the tubes are worn and not replaced in time, this may lead to feeding failures, filament accumulation inside the AMS, etc.