Have the shifting, cutof of the pressostat been checked up against a manometer on the steam wand ?

several things could be happening
one , is that the pressostat changes behavior because of things getting hotter and hotter(maybe softer membreme ?)

or the Manometer itself is changing
or both
but a test on the steam wand at startup, and after loong time would give info
just dont let the test manometer get hot ,

I have not verified the stock manometer readings with a second instrument. Good point. I do not have the gear handy to do so now, but may pursue this course if cleaning and or replacement of the p-stat membrane does not change the situation. Thanks for the tip.

Scott

FWIW I prefer to run the MCAL with a lower pressurestat setting, cycling between 0.8 and 1. I can leave it at that all day. I hardly ever use robusta blends, however.