High Johnny, I have the same problem with identical couplings, did you ever find ou the answer to this ?, I have spent hours trawling the net with no luck!
many thanks Ian. P.s. I was about to buy the same pliers, which I assume are no good for this application?
Many Thanks Johnny and Brian for the rally fast replies, I’m very grateful, I sHall buy the pliers as pictured and flood connectors with plus gas also, then give it a go . I shall also look out on eBay for second hand fuel lines with connectors, however if all else fails and I make a hash of removing them , can anyone point me in the direction of a suitable replacement connector that would be up to me job? Thanks again guys. Fingers crossed!