Impressa S9 problem

[BL!]

Is the coffee spout, coffee powder free? Ist the Crema valve in the brewing Unit (top) clean? You can also try decalcing your coffee machine.
Different quantities of coffee could be the Flowmeter. The Flowmeter measure the flow from the water.
If the pump sounds more quiete is something clogged after the pump. Is it more loud, then flows not enough water to the pump.

Thank you for your answer.
The coffee is basically powder free, always some tiny tiny amount comes in the cup but that's almost microscopic and very few.
The crema valve on the top is as far as I can tell clean (even though the hose is totally blackened).
The pump sounds a bit different, when the problem is "active" the pump is very quiet compared to when everything is working normally.
But the problem is intermittent. For example, yesterday evening the machine was on and I was sitting in the other room when I heard it shutting down (it shuts itself of after 3 hours of no use), then I could hear the normal sounds again, that is, the pump sounded quite good and also the water coming from the coffee spout. I then went ahead and cleaned the machine (with BND Kaffee Studios own tablets of course! :-) ) and run the water for a full cycle from the tea spout as well as steamed. It all went quite well but maybe not as good as when it works normally if I recall that correctly. Anyhow I did 3 full cleaning programmes with tablets just to run through the system as much as possible.

I will test to decalcify as you say and report back after that.

BTW, the service connector in front (as well as the loose cable hanging on the back where the PCB is, is that for connecting to a computer for troubleshooting? Is that something you sell and is that helpful to have?

Thanks!