HD8917 does not give water

Hello ! I rep. already longer KM ( Delonghi), however now I encounter a problem where I need your help. I have a Saco HD8917, which gives no water when coffee is drawn. Tea and hot water work. Ok, I know all the testing. I checked the, thank goodness not long, water path and I got stuck at the spout. So I can test it, I disassembled the BG and while I was at it I cleaned it, put the top and bottom in place and flushed it. No water comes. I turned the nozzle out of the spring, flushed it, and water came out. And now my question of faith: There are outlet nozzles with and without sliding piece. How is the valve opened, with the variant without sliding piece. In my opinion, this is not possible? The pressure builds up in the direction of the rubber plug and cannot get past it without external help.
Is it possible to simply install a nozzle with a sliding piece ?
MfG

A flow selector is installed in the machine. This calcifies quite readily. Inside is a spring-loaded rubber mushroom (similar to a crema valve), this is opened by the pump pressure and gives way to the brew group.

Waterway

When the pump no longer builds up enough pressure, the valve can't open.
I usually install a new pump, sometimes just a new ball and gasket.

Theoretically, it is possible to retrofit a support valve with slider, but then the inner workings of the flow selector should be removed.

The flow selector can be simply öfnnen.
Insert a 3mm Allen wrench from below, press slightly upwards and turn approx. 45 degrees, then the inner workings come out.

Good evening MrLed! I
have times a picture attached. The water flow goes from the flowmeter to the pump via the safety valve to the heater, via the small repiler ( blue circle) once up to the hot water valve and through the wall via the outlet spigot to the BG. The spigot is located as everything is installed. Nothing else is installed in the machine! I will buy a nozzle with sliding piece and test. More remains not! Thanks anyway !

I just see, the machine has no flow selector.

Was this assembled as it lies?
I would say that the spring with the nipple must be reversed.

Hello!
as I sit here, it was so installed ! I turn the spring, then presses the MAschine already when heating water through the valve into the drip tray, because the BG is still in its home position. If it then goes up it gets some water off, but that is so little that it is only enough to drip. Therefore my thought, there should be a sliding piece purely! Pressure builds up, the BG drives up and opens the valve.
LG