Leaking fuel connector

[TR5TRIDER]

Just removed fuel tank from my 2000 fuel injected Girly and when I removed the 90 degree male fittings found that one of the female fittings on the tank would not shut off and constantly pissed fuel onto the floor of my shop.These fittings are new ones I purchased & installed in Nov. 2014. I did order the parts using the p/n indicated here on this forum and both the firings appear the same but one leaks when disconnected and the other does not. I am therefore assuming, that since these fittings appear to be identical, that the leaking one is defective and not a straight thru (non shut off) type. Are these fittings (CPC branded) rebuildable or toss and purchase a replacement and is there any difference in appearance of the 2 types?

[JoeDirt]

There is an o-ring inside of the female fitting. I haven't tried to take one apart before... but the picture below might help.

[Timbox2]

Mine was doing exactly the same recently, the bottom one was leaking but had the valve built in. I replaced them both with new metal type fittings.  Now Ive got the old one off the bike Ive played with valve and stopped it leaking. Could be just a bit of crud has got in stopping it seal,or the valve has jammed off centre,  try gently pushing a round blunt object in against the valve a couple of times, it might reseat properly.

[TR5TRIDER]

Thanks J.D. the picture makes it clear where the o ring that is not sealing is located but I think too fiddly to try and replace, so will order new fitting.
Tim, I shall try your method as you point out it is likely not the o ring that is at fault as it is relatively new has not been asked to perform a seal until this first time, yesterday. Will try with a piece of tubing same o.d. as the male fitting as this should allow max. flow and best possibility of dislodging trash.