Thankyou for the advice Gentlemen
I cleaned the thread with a toothbrush dipped in petrol, it did a great job removing the old sealant and cleaning the thread.
Then worked round a rag inside to dry the thread. Maybe the fuel remained in a crack and is causing the issue.
I seem to have over-estimated the sealing ability of the sealant, which, I shall reiterate, never got to a tacky state. In the heat I was working in I would have thought it would get to a tacky state far quicker than on a cooler day.
I am very nervous using a more solid solution for filling the gaps, just my luck (at the moment!!) a lump will fall off into the fuel hole at the bottom when I apply the goo and screw in the quick release.
I shall have to clean it all out again and see if there is bigger crack than I have seen so far causing the issue, then select one of the mentioned sealers to sort it out. Things never seem to go to plan. What with my stretched petrol tank
, it seems the BMW god is against me at the moment.
I await with interest the answers to 1200gsceej's