Hi Listers,
Thanks for all the replies.
I believe when I purchased the 35mm a couple of years ago I was unfortunately sold 1-3/8". Consequently it now weeps.
It would explain an issue about core plugs being too small to do the job. I will ensure that I get Metric in future.
Many thanks,
Regards Mike Bate.
TC10200 - Cloudy Cornwall. UK.