Thanks for the reply Stikey, I checked and "Force scale" was off.
I figured it out….
The first thing I noticed is that when you hold down the track selector button and turn the pitch knob the progression of the red and green LED’s corresponds to a base 12 numbering system.
Hence LED 1 = red
LED 2 = red
LED 3 = orange
means the number 30 in base 12 or 36 base 10 which is the right midi note number for C2 (or C3 depending on which MIDI standard you use).
If LED 3 was red instead of orange and LED 4 was green that would be 31 base 12 or 37 base 10.
So…. why base 12? Hmmm…. there are 12 semitones in an octave.
Then I noticed that the semitones of the C major scale are silk screened across the top of the 10 x 16 grid.
This allows the note names to be read out directly. The green (or orange) LED is the note name and the number of red (+orange) LED’s lit on the left is the octave number of the note. So 3 red LED’s plus a green LED under the "D" is D3.
So far I haven’t found a description of this in the manual but I assume it’s there somewhere.