La Pavoni has been producing manual mechanical lever machines, le macchine da caffè a leva, since the 1950s. They are still producing them today with basically 3 domestic models: Europiccola, Professional, and the Stradivari.
Date your La Pavoni lever espresso machine. Or get an overview of specs of the Professional model from kaffeewiki.de (in German). Francesco Ceccarelli also has an excellent informative site about older La Pavonis.
(since 1950; MSRP: €525-880)
smallest tank, no pressure gauge (but can be added)
(since 2005; MSRP: €800-1500, depending on finish, with pressure gauge or not)
with a coffee grinder (separate?) and curved lever (what they call plinth?
This page is a collection of resources from my trial and tribulations of reconditioning several La Pavoni Professional models from the 1980s and 1990s)
http://www.francescoceccarelli.eu/
CAD model thanks to John Michael Hauk:
Boiler pressure should be between 0.6 and 1 bar. If it is not maintaining pressure and there is no false pressure (check this by opening steam wand valve for a quick blast to bleed any air and see whether it will maintain pressure once it reaches pressure again). Strip down completely to clean, maybe replace seals, and take apart the safety valve and check that nothing is corroded. Alternatively, if pressure seems fluctuate (getting too high, not getting high enough), check the pressure stat pipe, and if that is okay, the safety stat might need replacing (see how).
Illustrated guide of things to check if overheating on a Europiccola (in German).
Water trapped in the portafilter
Wonderful mechanistic explanation for this with a CAD model: