in this case a guy from the States thought he had scale in his machine as the brew temp was low

but there was no indication of scale in his machine or elsewhere in his house

he had normal boiler pressure indicated and no visible or audible leaks and plenty of hot water from the hot water tap

it could only be the piston seals (which were the original ones from 2014 i believe) allowing air into the thermosiphon, which will dramatically impair the efficiency of the thermosiphon and as a result the group will run noticably cool - unlike a dipper the group is not mounted on the boiler so the thermosiphon is what regulateds the group temperature - a compromised thermosiphon means a compromised group

this is his reply -

Hello Reiss,

Remarkable.  Machine making perfect espresso and Americanos. Water hot like I bought L1 yesterday. 

Now I will replace seals annually. Will not bother you anymore.  I have owned approx. 7 high end espresso machines and this one is by far the best. Would gladly buy again and if I live long enough I will do so. 

Best, Max Zupon.