PyramidHead76

Hi. Well, what I thought had fixed it hadn't, it failed again 75% through the next print. Then I switched to a brand new roll of filament and that worked 100% fine. I unrolled the problematic filament, wrapped it losely around a chair to try to reduce tension in it - And over the next 24h literally every winding just snapped under its own tension. I guess as geert_2 said, when that tension is all in the bowden tube & extruder it's just too much for the printer. Really all of these things we've changed are interdependent and help a little bit, but there are many combinations of things that might not quite add up to a successful print. But back to your specific problems: Your atomic pull results definitely look "interesting", with the twin tails at the end. It seems like maybe the filament is just about squeezing around a blockage maybe? If you don't have another nozzle to try, one other thing I've done before with a different printer, was to remove the nozzle, hold it over a gas stove (with long, insulated pliers) and physically poke the contents out with a metal rod. It's a shame there's no magic chemical that dissolves PLA in the way that Acetone can be used for ABS.

Thanks for your detailed suggestions. I think this was the key one, or at least started me on a chain of cooling-related things & it seems to be working again now. Although the fan *was* working, both it and the heatsink were pretty dirty. I took it all apart, cleaned it up with IPA (when cold, obviously), and while I was at it, added some fresh thermal paste around the isolator, and the equivalent aluminium piece connected to the top of the PTFE piece on a 2+. Before doing that, I noticed that your slow pull technique, and an earlier 'atomic' pull resulted in a almost-break high up the filament where I wouldn't expect one to be (see pic) - I guess what I was seeing here was that there was too much heat up above the PFTE break, and that was probably causing everything to go wrong at the first retract? Anyway, I'll see how it goes...

Hi all, I have an UM2+ (upgraded from UM2 by previous owner) in addition to 4 other 3D printers, and the Ultimaker is easily the machine that I've used the most. As per the machine stats, 3KM of filament has passed through it. But, I've started having extrusion problems in the last month on files which worked before. The machine just stops extruding, except at very slow print rates. As you can see, the machine hasn't had an easy life and it's probably time to replace some components. That's fine. I've worked through https://ultimaker.com/en/resources/11704-extrusion-problems many times in the printer's life, but it doesn't help this time. So, I've replaced or cleaned quite a lot already, it's still not working properly and I'm not sure what to replace next. What I've already done: * Atomic clean * New PTFE coupler * New PTFE bowden tube * Disassembled, cleaned, reassembled the extruder on the back of the machine, making sure the cogs are all seated correctly. There's little visible wear here, but it's a UM2+ addon, so has only been fitted for a smaller % of the machine's lifetime. Possible next items: 1. New nozzle (I can manually push material through so I don't think it's this) 2. New thermistor 3. New hot-end entirely 4. ??? So, for other long-term UM2+ owners in particular: What would you suggest as the most likely problem? Thanks! Neil