Descaling instructions bosh filtrino fast cup

It took me ages to get his to work - seems that on the THD2023GB (Black) Filtrino, you push and hold the temp. set button for 10 seconds to get he descale programme running.

From the manual, although I cannot get it to work.

-Turn the appliance off with the on/off
switch.
-Press and hold the start/stop button.
-Turn the appliance back on with the on/
off switch.
-Release the start/stop button as soon
as the DESCALE symbol lights up.

Running the descaling programme
-Remove the water tank, pour out any
remaining water, and reinsert it.
-Prepare the descaling solution according
to the manufacturer's instructions
and pour it into the water tank up to the
calc mark. A descaling agent approved
especially for this machine is available
from Bosch Customer Service (Article
No. 310967) or from specialty retailers.
-Place a container holding at least 500 ml
under the water outlet. The container
must fit the cup stand exactly and must
remain in place. Set the cup stand to the
lowest position.
-Press and hold the start/stop button for
at least 10 seconds to start the descaling
programme.
-The descaling programme will now
run automatically. The N icon flashes
while the programme is running. (The
programme runs for approx. 10 minutes).
The descaling solution is pumped
through the appliance in multiple phases
and then runs into the container until
the water tank is almost empty. A small
amount of solution is always left in the
tank.
-When the most recently selected
temperature icon lights up, the descaling
program has finished.
-Rinse the water tank thoroughly and fill
up to the max mark with fresh water.
-Now select and draw warm water three
times to rinse out the appliance. Do not
drink this water!

Use white vinegar, and not CLR.
Vinegar is a food source that will not harm you, or harm kitchen drain, and also excellent descaler that will not harm metal.
You can even soak shower heads in white vinegar for several days.

Now the exact technique: I would fill affected area, and let sit for a while, pour out, then repeat with more white vinegar.

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