I just did another check. The arpeggiator is working correctly. The reason why it was jumping up an octave on oscillator 6 was because I had the 'add lower octave' switch turned on. Which lifts the 6th oscillator an octave rather than add a lower one. With the octave switch turned off, all 6 oscillators play the same note. (phew)
Ghosting: when the poly is turned on, the ghosting is there for the first few hits. Waiting for a period of time between hits doesn't influence its behaviour (still present once the key is hit).
I did a quick experiment. First hit. The note had a fast beating, hit again a slow beating (more like a slow phase), push again a fast beating, hit again, then back to normal. (approx)
When using the arp the notes has the same behaviour e.g. the first few repetitions distorted/beating then normal. Once the note is sounding normal it stays like this until I hit another key. The note next to it can cause the same problem
Initially I thought it was the previous note causing the beating. but I'm not so sure now as the beating/ghosting seems to change with each consecutive hit until it seems to resolve.....
I will connect the oscilloscope tomorrow night and trace the oscillator wave (see if I can find where the ghosting is introduced)
Thanks again