Hi all. This is an update to this post. I don't know what else the community can do to help, but I figured I'd throw some more content up there and give something bored people to look at.
Since the last update on that post, I tried working on the printer in freezing temperatures (not really but it's cold in this house) with extremely precise practices on assembling the hot end (the same hot end I had haphazardly assembled dozens of times and printed with zero issues) and yielded zero progress. Today, I tried a brand new PTFE lined heat break, along with a brand new Capricorn Bowden tube (I already had one but I needed more tubing for the heat break). Clogging in the same exact way in roughly the same amount of time as every other attempt. It's as if I've not tried anything, literally nothing is effecting the results.
I considered ordering a fancy micro-swiss or ed3 hot end, but at this point, including the stock hardware, I've gone through 6 heat breaks, 3 heat blocks, a half dozen nozzles and a foot of Bowden tubing, none of which did anything to fix my problem (or even make it worse). I would look to the extruder, but I outlined in the previous post the testing I did to rule that out (able to run >1m of filament at high and low speeds through the Bowden tube).
I'm at the end of my wits. Perfectly good printer cranking out multiple high detail prints a day, now completely useless over something so stupid as clogging. Where the hell else can I look? Could it possibly be some sort of software/firmware issue, where Klipper isn't sending or receiving the right commands or something? I know my slicer settings are at least good enough because I've tried both prints that have completed dozens of times as well as new prints with drastically reduced retraction. Do steppers need to be tuned over time? I don't think it makes sense that after a year it'd suddenly become so uncalibrated it's unusable, and when I tried calibrating it before I was just unknowingly calibrating against mild clogs, but I don't know where else to look.
Hm, ok what you're saying makes sense. I am remembering that my extruder motor used to get pretty hot after long prints; since the jamming issue the extruder hasn't been spinning for more than a few minutes at a time, but maybe it should be a bit warmer than cool to the touch. I have a few other things I want to try, if those don't give me any info, I might try running a long print with no filament (or disconnecting the tube and extruding cold filament) and seeing if the extruder's temp changes at all. Thanks for the advice.