So the problem this helps solve is keeping the PTFE below it's toxic off-gassing temperature. This will help somewhat, especially for shorter prints. I wouldn't trust it for long prints (12+ hours? unsure) without testing.
I'm planning on upgrading the fan on the side to a 40x20mm which should just be longer screws but a direct replacement. I also recommend getting a length of Capricorn PTFE, which from my research, is the most heat resistant tube you can get. Careful to buy reputable, apparently lots of knockoffs. https://www.amazon.com/dp/B079P92HN9
This guy disassembles the Artillery all metal. The lever is metal, the heater cartridge is different (hotter maybe?), the nozzle is hardened steel, heatbreak is different...
https://www.youtube.com/watch?v=iyr0Mg9AI6Y
Here's what I purchased.
https://www.amazon.com/dp/B09VYWT8T9
Also read this other comment I made, as I'm not exactly thrilled with it.
It sounds like you’re on the right track for troubleshooting. Your under extrusion might be caused by the PTFE liner. It is another common issue that occurs with this printer and is covered by the last part of Joel Telling’s review video. Check the PTFE liner and replace if deformed or gunked up with filament. It’s inexpensive to replace with some Capricorn PTFE.
The idler arm may be intact now, but it would be a good idea to buy the metal idler arm for when it does eventually break.
You don’t necessarily need a new hotend or extruder yet, unless you print high temp filaments like ASA, PC, Nylon, etc. Upgrading now might introduce new problems for you to diagnose. Use the stock setup and get familiar with it. After that, you’ll get a good feel for if you need to upgrade or not.
Thanks. I actually ended up at Capricorns website and found their authorized resellers on Amazon.
No extras, but this is authorized - https://www.amazon.com/gp/product/B079P92HN9/
You can just cut it back 1cm or so and try again...but I would also order a replacement pack of the fittings.
These are for the ADV3 but I think will for for you too: https://www.amazon.com/dp/B01NANKRTD?psc=1&ref=ppx_yo2ov_dt_b_product_details
While you are there you might want to just grab a capricorn tube for $10.
https://www.amazon.com/dp/B079P92HN9?psc=1&ref=ppx\_yo2ov\_dt\_b\_product\_details