1210 hydraulic leak

I'm back again looking for help with this 1210. Thanks to a link from RGMartin, I think I now have the electrics sorted out. Now on to the hydraulic leaks. I believe I have a handle on all but one. This is a selectamatic, with twin stack pump. It has a combining valve(?) mounted under a single remote valve, with a two position spool/knob assembly on one side near the front. Near the rear, on the same side, is a round cover plate held on by two small bolts. This cover has a hole in the center, from which hydraulic fluid dribbles constantly when the engine is running. I have searched the parts book for this cover and/or what's behind it with no success. I can find the valve(listed as K919808) on only one frame, along with the related tubes/pipes, bolts, O rings, gaskets etc, associated with it, but no sign of this cover or what might be under it. I'm working up a list of O rings, gaskets and such for the other leaks, but don't really know what to look for with this. My I&T gives a pretty good rundown on most all of the hydraulics, but once again I don't see anything related to this valve or what's in it.
Anyone out there have any ideas/experience with one of these, and/or some clue as to what might be leaking?

I am having a hard time following your description. Any chance of a picture?

The only things that come to mind are the combining valve(puts both halves of the pump flow to remotes, or splits and sends one half to 3 point), and the dump valve(used for rapid depressurizing the hydraulics, like lowering a single acting cylinder on a dump trailer).

Either way, and leak is probably just a handful of worn out, common size O-rings...