If you want sloppyness try using a 1/4 rod by mistake in the BTH then afterwards you will know sloppyness (assuming you can get it out!)the early BTH used a socket head cap screw, the later BTH are using a brass straight slot thread section.
I just called Tom Healy and he can, lucky for me, supply this plug .
I can find 7mm hex bolts 30 miles away.
I can buy choices to cut off on eBay.
Thanks to all, my sloppyness is very frustrating.
I should have put my timing plug in a plastic bag.
I recommend Coventry spares for Vincent parts.
Cheers
Craig