Hello forum members,
I think I have found a solution.
The issue was with the potentiometers.
The values of the 2 wipers were being summed together.
If one potentiometer was at, for example, 7k and the other at 5k, then there would be 12k between the 2 wipers. In that manner, they were influencing each other.
Naturally, the Arduino would react incorrectly to this.
This was due to the way they were connected to the Arduino.
Tomorrow, back at the workshop, I will connect them only between the Vcc and the wipers.
Hopefully, this should work.
Regards, Michel