I suspect from your comment, if you are only using one circuit for the lifting/lowering and that is when the oil flows out the drain hose onto the ground, it will be one or the other of those two O rings that is leaking. I just can't recall if the 9300 series tractor has the multiple or single hose system for the drain as its a lot harder to sort it out if its a slow leak and no idea which of the circuits on the bank are leaking vs if there is a dedicated hose for every circuit.
Check the male ends as well for any wear/sharpness or roughness that could cause it to damage the O ring while your at it as its not a lot of fun changing those O rings to get them to seat into place. Also not sure if they were still using the normal O ring as our 9430 I see uses a special flatish type unit and then the orange plastic backup ring.
With a leak that bad you may be able to clean up the SCV inside and actually see which one has the damaged O ring with the use of a small flashlight