Siemens EQ9 S300 Leakage, but where?

Hello,

We are using the above machine. The problem started when the message came up (meaning) "Carbonated and/or ... Fill in water" - sorry, I can't remember the entire message.

I then replaced the hose on the brewing unit as the old one was hardly letting any water through and then I cleaned the flowmeter, after which the message disappeared. But since then, the desired amount of coffee no longer comes out of the machine, but about 1/4 to 1/3 less. The rest ends up in the middle drip tray.
The desired quantities are only dispensed with milk and hot water, which indicates to me that there is a leak somewhere in the brewing unit.

With the brewing unit removed, I can't see a runner at any of the water inlets or outlets that would indicate a leak.

At first I thought it was due to the new hose, because I tightened the ear clamps without the appropriate pliers, but with the side cutter. Now I have bought new clamps and the appropriate pliers and fitted them again, but the result is unchanged.

When I completely dismantle the machine, it is dry inside, there is no water anywhere. I also checked the other hose connections on the brewing unit again, but they are all sitting as they should.

Before I buy a new brewing unit for a lot of money (which would be the third one after four years...), I wanted to ask the experts in the forum if you have the golden tip for me.

Best regards
Marco

Sorry, please delete! I got the error message "504 Gateway Time-out" twice when sending, so I assumed that the post was not sent.

Greetings
Marco