I'm here to report that there has been some success---there was a remaining gasket that came out like hard plastic and yes two holes see pic..

now another dilemma -- how to get the enough torque to get unit unscrewed....I made a device out of 2 wood blocks screwed together...see pics...but the unit is so tight that the allen wrenches that get inserted into the holes actually break off under the torque of try to unscrew the unit...even after soaking with liquid wrench over night...any thoughts...this is turning into much more of a project then expected, but it is such nicely preserved La Pavoni I hate to quit.
Thanks, Bob

I made a tool to do this: Info needed on 'La Cara'
Others on the board have done this with much greater sophistication.

Good that you found the holes hiding in there after all, so there is hope, and a lot less bashing. The trick now is to get the torque moving in the right direction, in the same axis as the threads. I have had a lot better luck with the flange tool I make, even though it is pvc, than the two nails, punches, hex wrenches etc, and in your case this is complicated by the fact that the group is still on the boiler, as I assume it is. The cylinder does not seem to take a lot of force, just the force applied in the proper direction with no wobbling or give in the tool.

I commend you on trying to make this tool One thing you need to do is make the 2 allen pins as short as possible to avoid loosing torque to through twist and bending. also support the tool from underneath so you can concentrate on turning forces. I do not know the OE tool but I am surprised that PVC has enough strength in shear to do the trick. but is that works great as well. My inclination would be to use black pipe of the right diameter and and grind down leaving two prongs.....I've done this in other awkward situations, and as stated above, keeping engagement (pushing) force while turning is the challenge.