I used a propane torch to help cook the gaskets underneath, let it soak in penetrating oil and hammered it both ways today. Then I drilled and threaded holes, inserted bolts, and used my own rough spanner. Still no movement. This reminds me of the agony of removing rusted bolts on my Conti Prestina project. It's a real stuck point. I'll keep you all posted. BTW I am trying to turn it out counterclockwise.

Thanks, Bill. I tried an oil filter wrench. No luck. And I have the group cylinder tool from Orphan Espresso. I'm going to give it another "go" this morning. Persistance. Patience. Caffeine.

SUCCESS!!!

In the end, better clamping and the use of punches to loosen the ring in both directions worked. I think the core problem was that the brass ring was welded to the baked gasket underneath. That bond needed to be cracked loose with the percussion of hammer against punch. I finished removing the ring with the crude spanner I fabricated out of aluminum stock and bolts that were inserted in new, threaded holes drilled into the brass ring.