Thanks for that. In this case the sensor is a Honeywell rotation sensor 90 degrees. I found some data on it and it should be full left = 0,5 volts - full right = 4,5 volts. And in one of the posts here someone mentioned the centre should read 2.1 volts.

The other puzzle for me is when we connect the curtis handset to the main controller and monitor the inputs, the forward and reverse connections are reversed. When we activate the forward control it shows as reverse on the handset and similarly when we activate the reverse control then the monitor shows forward. I wonder if you, or anyone can shed some light on this ?