Give Danny Richie at GR Research a call or email. He had had at least one Magnepan model sent to him for evaluation, and he posted a YouTube video in which he discusses and demonstrates what he discovered. As he regularly does with loudspeakers sent to him by customers, he designed a new crossover for that Maggie.
Ah, here it is:
https://youtu.be/_bpDP0jxj4k?si=yZDkiel-87wgTzEY