PLA plugs above hot-end on UMO

[jameshs 42]

definitely worth looking at the nozzle/brass tube connection rather than the bowden - if that is a cold pull plug then the rim is at the top of the nozzle, nowhere near the bowden.

Make sure the brass tube is low enough that the nozzle when tightened has a few mm from the head block - then you can get a proper seal by carefully tightening (by careful i mean careful!)

it may be academic though, as at full temp that area should be molten - in my experience there are just bad reels, and reels that are almost bad so that in the last 25% (harder tension) they become blockers - I save those for my larger nozzles.

They can also tend to snap if left in the machine overnight (but not always). I have a few designs (plant pots, plant pot feet, bike clips, resin mixing cups) that I print with these 'ends' through larger nozzles, and the designs also have few retractions.

Satisfying to use up those problematic filaments.

[derek-bosch 1]

the advice to have the brass tube tight, and the nozzle a little lower seems opposite from the assembly instruction manual, but I will try it.

I will also try a fresh spool of filament to see if my woes go away... hate to waste 25% of the spool though - time to invest in some larger nozzles

[derek-bosch 1]

well, the good news is that things seem to be working for now.

I'm not exactly sure what the exact thing that fixed the problem...

I did tighten the nozzle / brass pipe.

I also installed a replacement fan for the nozzle. The prior one had broken and I had been running fanless for quite a while - I think this was main problem...

Been running all weekend without a single jam. On the same blue filament that was giving me troubles. And a new spool of red which is working fine too.

I probably will install a hot-end fan above the aluminum block as others have recommended.

But happy to be printing again!

Many thanks for all the advice and help.