Hey man, sorry to hear you’ve been dealing with this for so long — sounds really frustrating. I’m actually in the same boat… Slots 3 and 4 keep throwing pull-back failures for me too. Interestingly, things work fine if I disconnect the PTFE tube from the buffer, so I’m starting to suspect the buffer might be the culprit.
Have you ever tried replacing or upgrading the buffer, maybe to the 4-way version? That’s what I’m thinking of doing next, and I’d love to hear about your experience if you’ve gone down that road. Really appreciate any insights you can share — thanks!
The python upgrade saved me from spools jumping and jamming and motor overload issues. Also means no more respooling as I can run big spools, small spools, cardboard spools, heavy spools, light spools.
I was having issues with brand new full spools overloading the AMS motors and empty ones jumping and jamming.
I took the buffer off and cleaned it but I’m not sure if thats the issue. I’m suspecting its the 4>1 hub inside the AMS again. Now that I have 2 I can replace pieces inside and swap them over. My first hub died from one of the little fittings metal tube grip pieces breaking and of course you cant just buy one of those. BUT you can buy an adapter that has 2 of them in it so I can rip that apart and get my old hub running and swap them out.
I’ve done sooo many upgrades its nuts. I printed a door mod last night which lets you open the P1S door a full 270° and actually rest against the left side panel.
But on to your issue. My first pull-back error was actually the ptfe tube at the last bend at the very top of the extruder. Without an AMS riser its a bit of a tight bend and wears out quite fast. Check that and also your ptfe tubes inside the AMS. When the tubes wear they get grooves worn in that kinda grip instead of glide. Removing a small amount of friction anywhere (like the buffer for example) will help alleviate the symptoms but not fix it.
Just got out of bed so thought train running wild. Any longer and I’ll need to add chapters XD.
I had been dealing with this issue as well. Ultimately i found the roller had swelled slightly which ended up causing the spool to cant when attempting to retract.
I pulled the roller assembly and was able to reseat the rubber sleeve with some superglue.
I only found this issue after replacing multiple PTFE tubes, rearranging the AMS (i have 4), and installing multiple AMS mods.
Ultimately, i ended up finding 4 rollers with the same symptom across all four AMS.
Since that repair, i have removed the AMS mods and reorganized them back to their original location and have yet to have another retraction issue. This is even with printing some abrasive filament.
Not saying that this is the source of your issue, but it is another possible failure that leads to the same outcome
Any thoughts are always appreciated whether wrong or right. I’m working with support but due to time differences its slow going. I’ve removed my internals from my python so its just sitting on the table without an enclosure. They suggested I open up the 4>1 hub and check for blockages or issues. Since I already replaced this not long ago I thought it might not be the issue but I had fixed the faulty one so a simple swap should work.
But.
I still have the same issue on the same 3 slot. I’m starting to think its the feeder. Which I’ve been avoiding as that is a pain in the butt to remove with the python mod. It has to be the 1 downside (which I overlooked as I have never had issues with the feeders… *sigh).
I might swap over 2 feeders and see.
I will keep your thought playing in my mind though.
My issue was a little different. I didn’t have any stuck filament. As it turns out my AMS 2 Pro pulled the ASA CF back and it came out of the feed tube from the spool. This left the spool spinning telling the AMS that the pull back had failed. The AMS thought this was a broken filament and gave the message that pull back had failed. I tried several things thinking it was clogged in the tube or feeder somewhere but it wasn’t. This led to a loop where it needed to be cleared and pulled back, but there was nothing to pull back in the tube. I fed a line of the ASA CF into the tube manually while the unit was powered down. When I powered back up the unit went through its routine and I was able to finish the manual pull back routine allowing the AMS to clear itself from the loop. This was just a sensor glitch in my opinion. Very frustrating one at that.