how can I fix my worcester 9.24 electronic?

the 22mm bulkhead isolation valves leak a bit so I have bought new ones, unfortunately my old ones have 21mm of brass thread on top against the new ones at about 15mm, should I try to lever the nut and hopefully the olive down to reach the valves or should i keep trying to find the original 21mm thread valves. My only alternative is to get a 22mm compression pipe repair and get a friend to cut additional thread on it. Anyone any thoughts?