CJ,
I have the Hill MK2 and have had it for almost a year. It has been used to fill a tank approx 215cc to about 3,000 psi and is "dumped of moisture" via the pressure relief valve usually once per fill. I have not replaced my desiccant, still on the original pack. I also put a plastic bag over the top of the intake and attempt to seal the "air" out of the desiccant between uses.
I just inspected my pressure relief valve and noted a "black" discharge, small amount. I then took off the high pressure hose and inspected the hose and the respective high pressure port and threads and found absolutely no moisture or black residue. I am just wondering based of course on some of your other answers that maybe by pumping the bobcat to working pressure (with a much larger pressure cylinder) and without "draining" the moisture occasionally, that it has pushed the moisture over into the high side port of the pump and thus possibly into your bobcat? I hope not, but it is just an off the cuff idea?
Looking at your pics, maybe you could take the fill probe off the other end of your fill hose and see if the moisture has made it all the way to the probe? maybe not? (trying to be hopeful)