Opening front group of a Wollensak 190mm enlarging lens?

I just picked up one of these that has slight fungus in the front group. It looks like the front group may unscrew from the barrel but it doesn't, at least with the force I can apply by hand. The front trim ring (with the lettering) looks to be threaded but it didn't give with my hollowed-out rubber stopper. I haven't tried seeping acetone into the threads yet.

Has anyone ever been inside one of these? Is removing the trim ring the right way in? I'd really like to clean it up as the coatings are really nice, it would be a good lens for the 5x7 conversion I'm planning for my Beseler 45.

Set with threadlocker, treat with acetone and try again.

Charles, it may just be corroded. Some of my Enlarging Pro Raptars' cells come apart as they should, others don't.