Holy cow that needs a cleaning. I'd be dropping that pump and crawling in there with some diesel fuel and a stiff brush. I'm not sure that you can tell what might be going on with all of that goo (or maybe I am just staring at that). I'd think that if it was picking up any of that you might have all kinds of erratic things going on with the hydraulics from valves getting debris in them.
Once it is clean, put the cover on the workbench and put his jig on. Do it twice to make sure it is how you want it. Then button it up knowing you aren't going to have to get in there again. Just my 2 cents.