Anyone?

How do I remove the metal filler housing? Is this shellaced or is it just so tight-fit? Heating does not work in my case (although I managed to remove the hood by accident, which I did not intend to do...) and it just won't move even a little.
What technique do you use to open the thing? Thanks

Also, what's the sac size? It's 17 1./2 necked for the "regular" 21, but the one in 21 Super seems much smaller than that...

woodbin sells a sac they advertise for 51's but's too small for 51's, in my experience they work great on 21's and aero demi 51's. It's plastic, tapered and ribbed. It also works great for 75 and aerometric style converters. As for the metal casing, I use direct flame over the metal and they carefully pry it our by hand, applying GENTLY AND SUBTLY side motion while I pry out.