[EDIT] In case anyone finds this thread and is running into similar issues, I was able to resolve the problem with a new extruder. The gear in particular on my old extruder had worn pretty significantly. I replaced the gear, and the whole extruder with an all metal setup. I'm still dialing in settings to fix stringing a bit, BUT I am printing successfully again

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Basically the title, I usually can do basic repairs and upkeep for my CR-10S, but the issues I have going on right now I just *can't* figure out how to repair and it's driving me up the wall, I've wasted so much time and so many parts trying.

I noticed my printer starting to string a *lot* more than it had ever done before, even lowering the temp from 240 to 220 didn't really make any sort of difference. (I've been using 3-D Fuel Pro PLA, it's temperature range is marked at 210-240) but since most of what I print ends up being sanded down pretty extensively I didn't worry about it as long as the pieces being printed were solid, which they were.

Then it started having problems printing larger parts. Anything with a smaller footprint would still print just fine, like a benchy or a cali-dragon, but larger things started failing during the first layer. This happened a few times after cleaning clogs out of my printer, so it's probably a leveling issue right? Nozzle just a little too close to the bed during that first layer could easily make a clog if it spends too long not being able to push filament out right?

Well... either I don't know how to level anymore, or that didn't work. I've tried purposely leveling a little higher just in case, as well as a little lower, and where I *think* just right is. At this point I really don't know anymore.

I've replaced nozzles just in case I wasn't cleaning clogs out well enough (and I've made sure they're the same 0.4 size that my slicer thinks I'm using). I've done the same with the Bowden Tubes - to the extent I've gone through almost two replacement kits and only have enough couplings left to try one more time.

I've disassembled the hot end and cleaned it out after the bigger clogs, and done it again a few more times as I kept getting failed prints to ensure things were clean. Yes I've reassembled everything hot so there's no gap between the nozzle and the Bowden tube inside the hot end.

I've switched filament profiles in Cura (I think the stringing started when I switched to the filament profile specific to my filament. I used to print successfully with the generic PLA profile). I've switched to filament rolls that I've used successfully in the past (old rolls that had maybe 50-100 grams left on them, too small for prop pieces but enough for testing). I've tried temperatures from 200-210 in case I was printing too hot and that was causing clogs.

I've tightened my belts, tightened the mount plate for the hot end (it was wobbly, I thought that might be affecting my bed leveling). I replaced my bed (I use 12"x"12"mirror sheets) in case it was warped. Nothing is working.

I'm at a point now where I can't even get a Benchy or a Cali-Dragon to print. I can get the first layer down fine, then 2-4 more successful layers, and then the print will just start to spaghetti out of nowhere - with the layers that were successful still being attached to the print bed - so at the very least I've ruled out a bed adhesion issue. I *think* the leveling is alright now, the purge line doesn't stick to the print bed without any adhesion (so I'm not too close), but the first layer of the print will still stick with the basic glue stick.

My extruder still seems to be working fine pushing filament, I haven't noticed it clicking or slipping or grinding my filament (well, it'll grind when the whole thing is clogged up but that's a symptom not a cause). The hot end itself isn't having any temperature issues, so I haven't considered replacing either piece yet.

I'm so completely out of ideas on what I can do to fix this, I don't want to keep throwing money at parts that aren't solving my problem, please what am I overlooking?