Thanks Matthew
Possible electrical issues had crossed my mind too. The bike has a VAPE kit fitted, and appears to have anew HT lead, so I was excluding that for now. But of course all this troubleshooting is a process of elimination, so I will certainly look into that further. I’ll post again if/when I find the solution.
I wouldn’t have thought that it would be a characteristic of the bike, as it is quite intrusive whilst riding.
Pete.