Hey. A couple weeks ago I got my old ender 3 pro out of the basement and have been trying to get a decent print with it ever since. I managed to print out one benchy without issue, but ever since then every print I do would be plagued with awful underextrusion.

I've replaced a few parts, including the hot end and the nozzle, and even did this one hack someone suggested where you put a piece of PTFE tubing in the hotend, but no matter what the issue persists. My thought was it might be the creality filament I ordered, so I ordered a spool of hatchbox filament. But the problem ended up being worse on the hatchbox filament. I've put both in a filament dehydrator but it's made no difference. Both spools have tough sections along them that don't seem to melt as easily when I pull them out of the extruder, so I'm thinking that might have something to do with it.

Turning the print speed down and increasing the flow and temperature yielded better results, but it was still underextruding on every other layer.

I want to know if there's something I can or should do before I just give in and buy another roll of filament. I've probably spent enough at this point to buy a better printer, but I guess that's sunk cost for ya.

Edit: SOLVED! I just forgot to tighten the extruder tension arm, now it's working perfectly. Thanks to @brettvitaz@programming.dev