AMS is flashing red on one or more spool slots? Here's how you fix it...
PREFACE
It will flash red for lots of reasons... For instance, while loading the filament, grab the spool so it won't turn. It will try three times, then fault out and flash red. No dissassembly required. Trouble loading all the way to the extruder, for one reason or another. Flashing red. Dissasembly of the AMS won't help. Broken filament in the extruder, flashing red in the AMS. Once again, won't help. And not always necessary to turn off the printer. What if you are in the middle of a print? Unless you can get it dissassembled, fixed and reassembled before the bed cools off, you will lose that print. Check the Bambu wiki FIRST before trying any of this, please. I accept no responsibiliity for for user error.
You will need
1 x Hex 2mm screwdriver, 1 x Hex 1.5mm screwdriver, 1x brass wire brush, 1x sprayable bottle of IPA
TURN OFF YOUR PRINTER!!!
Step 1
Remove the hub using a 2mm hex screwdriver from the rear of the printer and pop out the bowden(s) by pressing down (I did it with the 2mm hex driver) on the bowden coupler.
Remove all filament from the AMS manually.
Unplug the AMS black plug from the AMS.
Move to a workstation such as a desk and bring the AMS with you, including the bowden hanging out the back.
Step 2
Open the lid.
Push down the 3-4cm wide bowden coupler to remove the external bowden and put it to one side; it's symmetrical so easy to put back in.
Using a 2mm hex driver, at the rear of the AMS, on the right and left deep inside are two holes - unscrew the screws. Be CAREFUL because in the next step they will probably fall out so don't lose them.
Lift the body of the AMS out but do not pull too hard as there are two JST crimped wires at the rear; pull those out - remember the left one is a 6 wire and the right one is a 2 wire; it's fairly obvious.
Step 3
Turn the internal large package upside down.
There should be a small, roughly 6cm by 3-4cm black panel. Use a 1.5mm hex screwdriver to remove the 6 screws - do NOT lose them; put them to one side.
You should now be able to remove the 4 bowden couplers at the top and 1 at the base.
Now, CAREFULLY snap pop out the black piece of plastic and without taking any wires out, review the internals.
You are probably seeing some grubby internals at this juncture.
Be careful not to pop out the magnets at the top where the bowden couplers were; I didn't but a friend did and they are a hassle to put back in.
Spray some IPA on the messy areas and check both the piece you removed and the piece in place, then use a wire brush to carefully brush off all the filament.
Hard work done - now to put it back together...
Carefully place the bowden (x5) couplers back; the bottom one will be a touch loose but don't worry.
Snap fit the black piece of plastic and carefully hex driver the 1.5mm screws back in; tight but not overly tight - remember you may need to maintain it again in the future and you don't want to damage the screws.
Turn over the internal casing and carefully reinsert the 2 wire and 6 wire crimped black wires into the rear of the AMS.
Now, slide in the larger bowden coupler to the rear of the AMS.
Now slide the AMS into place and screw in the 2mm Hex driver screws into the rear left and rear right of the printer.
MAKE SURE that the bowden that you will now be feeding in from the rear of the AMS once closed correctly feeds into the bowden coupler.
Now, connect up the black wire to either the printer or a daisy-chained AMS.
Reinstall the hub on the rear of the printer using the 2mm hex driver and insert the bowden that comes from the rear of the AMS firmly into the hub.
Turn ON the printer!!!
All should be white lights so please try and feed spools of filament into every slot of the AMS.
PRINT!!!