A new spool of retina-burn orange PETG snagged when the takeup guide let the filament fall off the inboard side and the extruder tightened the loops around the spool holder. I carefully unwound the loops without removing the spool to ensure I didn’t introduce a crossover, scraped the bird’s next off the platform, and restarted the print.
After undoing the second snag, I added a crude spool sidewall:
It’s decidedly unlovely, but I was in a hurry to get a PCB holder printed and ready for use. Worked perfectly!
I’ve rarely had a problem with any other spools and I don’t know what’s new-and-different with this one.
The Smell of Molten Projects in the Morning 
I have had good luck putting a piece of PVC pipe just below the reel to not let the filament get outside the side of the reel
I like the idea, but, now that I look at it, the M2’s frame has absolutely no holes anywhere near the pulloff side. Maybe I can just stick a flap to the frame, so it extends across the spool and forces the filament through a definite opening?
Better than a cardboard sidewall, fer shure!
Thanks for the suggestion …
I used blue masking tape after I figured out that my frame was aluminum. Also thought about a bit of Velcro. But I am sure you can come up with a better idea. But a couple of pieces of sheet metal should probably fix the magnetic issue
Turns out there’s a strip of (real 3M) Velcro holding the RPi to the other side of the frame; it’s got a good track record. [grin]