Possible cause of quality issues and random freezes on long prints: curtain behind the printer  

Possible cause of quality issues and random freezes on long prints: curtain behind the printer

Posting this in case it helps someone else.

I am running a Prusa XL 2-tool on firmware 6.2.6. My printer is set up near a window with a curtain behind it. I did not think much of this at first, but it turned out to be affecting the machine in a couple of ways.

The curtain was occasionally brushing against and grabbing the cable and tube bundle above the toolheads. That seemed to interfere with motion and mess with print quality. The toolheads really do not seem to like any external drag on the harness.

At the same time, the curtain was blocking airflow behind the machine and trapping heat around the stepper motors (those things were HOT). On longer prints, I was seeing strange behavior and in some cases the printer would freeze entirely mid-print.

After moving the curtain away from the back of the printer, print quality improved and the freezes on long prints have not come back so far. That makes me think the issue was likely a combination of the harness being interfered with and the steppers running hotter than they should.

Nothing about the setup looked obviously wrong at first glance, so this one caught me off guard. If your XL is near fabric, curtains, or anything that can touch the cable bundle or restrict airflow behind the machine, it may be worth checking.

Hopefully this helps someone avoid a few hours of troubleshooting.