>>3533188>>3533204>>3533302As you're loading, periodically push the film in and out of the reel, like you slackening or tightening it. If it binds and you can't shimmy it, it's skipped a wire. You should be able to shunt it in and out of the reel a few mm, at all points in loading it. Same with 120.
Can't seem to find a video demonstrating it, but I saw one once, and it was like a lightbulb coming on.