@ATTAK Z, not had any problems with 5th to 6th, but will keep an eye on it.   Thanks for all the great advice everyone, going to get it booked in for a service as soon as lock downs over.    I do have a little tip for anyone with a similar issue, I've noticed it helps improve the gear change if I rev the Zed to over 3000+rpm in first, the throw is much smoother even when cold, been doing it for a few days now and it's transformed shifting.