I have my Bambu A1 set up in a very tight space, so I made use of the AMS Micro by emics to mount my spools vertically.
The printer is able to reliably load and unload filament from all four spools, but during printing (especially slot 4, the topmost spool), particularly after retractions, the extruder will be unable to re-insert the filament and will throw an "extruder is not extruding normally" error. I can manually push the filament in until it's grabbed by the extruder after which the print will continue normally until the next retraction.
The spools spin freely on the stock AMS hubs and the PTFE tubes are short and not worn. Any advice would be most welcome
Have you tried moving the spools around? Could be the AMS system is struggling with that one specific tube, or it could also be that the curve in the filament is making it hard to pull it into the extruder.
You could try feeding a lower spool into the tube that is currently holding the upper spool to see if that changes anything.
That's a good idea, I'll try that
No dice. Slot 4 fails most frequently but all slots are affected one time or another