o-rings look fine,It will be one of 2 things either the cup seal or a ring has gone on the ram, if you have a spare piece of macro line use it like an ear trumpet to see if the leak is coming from the small hole under the breech block, if it is then it is the cup seal may be a bit of dirt may be knackered, if not it is the ram o ring nearest the hammer
what the cup seal?
Thanks
Tom