Is it an optical illusion, or is the media pinched in at the center a little? Looks like an hourglass? If so, that's new for an M1 in my experience.
Little of both, it’s definitely deformed and a bit wavy in the middle, but not as bad as the pictures look.
DR, does the center tube have holes in it, or louvers?
Looks like it did the job. Thanks for c&p Robert
You’re welcome of course, it did do the job.
Worth mention that it was in service for about 18mths and is an older filter, Oil was 5/30 EPHM.