In the picture below you see the three on the left (Astoria type) are just a bit thinner than the Cimbali type on the right. I decided to use the Astoria seals which are more flexible. They are very much like the ones I am used to on the Londinium machines.
The inside of the group with the sleeve out:
Re-inserting the sleeve after cleaning and lubricating:
It goes in a little bit deeper than this:
Then on to the seals. I use a little spoon without any sharp edges to take off the old seals:
I could use the same spoon or an allen key to put the new seals back on but I took the opportunity to try out a tool that Stephen Sweeney made. This makes it extremely easy to slip on a seal. Just lubricate the shaft well, slide it over to the place on the piston you want the seal to end up in, and smoothly slip the seal over the shaft into the groove.
Second seal on:
Third, and done! Thanks Stephen!
The picture below is from Reiss Gunson, who had a Cremina years ago: