Have you tried a rubber washer akin to the ones that drags sell for the single rocker box inspection caps?
No I haven't Keith. How does that work?
Last week I went to the opticians to have my ears de-waxed, clearly successful as my bike sounded like a bag of nails on the way home
. Whilst I was there I made an appointment to have my eyes checked. It's years since I had my eyes lasere'd and thankfully I still don't need glasses. The optician did the pressure test on my eyeballs and he was most impressed that I didn't flinch, I said I'm used to this sort of thing, my eyes are pressure tested most days with wings attached. I know he said as he removed the remnants of one that got in my eye on the way
A lovely 1958 Velocette parked next to me as I arrive at the Optcians, we got chatting for nearly too long!