Factory-new KH Director completely non-functional. Titration timeout on every run!

Hi,

I've had the KHD running with the SA Doser 3 for 5 days now and unfortunately the unit simply does not work. I've burned through almost the entire reagent bottle and most of the calibration fluid without getting a single sensible measurement. I always get the titration error "titration takes too long." What happens during a measurement:

With a 65 ml sample, after filling, the cell sits at about pH 7. The unit then starts adding reagent, the pH ticks up slightly, then slowly drops to about pH 5.4, rises again to 5.5, and then the measurement aborts. Setup details:

Unit is sitting perfectly level
Sample tube including filter is 230 cm long, real volume 32 ml (38 ml calculated)
Calibration of sample and waste pumps: 75 ml/min and 73 ml/min
Reagent doser calibration: 8.2 ml/min
pH probe is seated fully, up to its mechanical stop

No air anywhere:
The sample filter is mounted vertically, so it doesn't trap air bubbles
I watched both the silicone sample line and the PVC reagent line throughout the entire measurement; not a single bubble
Tubing hangs straight

Via self-diagnosis I can hear the stirrer and the valve operating, and I can still hear them while a measurement is running
Results:

Out of about 40 measurements, only 2 returned values, ranging from 10 to 13 — both with calibration fluid. Aquarium water (also KH 7.5) behaves similar. What I find suspicious:

The probe will not push all the way into the unit. It hits an internal stop before it reaches the nut/fitting. On top of that, the nut is white, not black. That seems odd to me, because the ION Director is the unit that uses the white nut. Could the wrong measurement chamber have been fitted to my KHD? I really do not understand what's going on. As mentioned even unter titration the PH goes up by 0.2 as it hits 5.4. This I really do not understand.

I have already opened a ticket, but the response from GHL has not been helpful. Even when I use 100 ml of sample, I see exactly the same behaviour. I also manually increased the reagent flow rate so that it doses more; no difference whatsoever.
This device is 5 days old. Once again: either GHL provides a proper solution, or sends a new, unused replacement unit (as I'm entitled to under consumer protection law in my country).

Kind Regards