This is something I've ignored for awhile, but it keeps cropping up, and occasionally, if the filament snags real good, it can mess up a great print half way through, etc.

Basically I have my filament spools hanging on a PVC pipe mounted directly above the printer, and the printer just sucks it in from the spool, but occasionally it becomes knotted at the spool, or becomes otherwise tangled.

I'm thinking even if I completely unwrapped and rewrapped all of my spools so there was no trace of a tangle, what's to stop it from happening again? -- What's a good strategy for managing this kind of issue?