Well, I don't have the answer to the question posed above by me, but we did get a solution. Working on the rig the following day in better light, we found the wrong hose was being chased once it got into the web of hoses under the hydraulic tank. The one we were after ran direct to one of the pumps and was MUCH easier to access. No tears will be shed if we never have to get at ones of the lines going through that bulkhead plate and we'd still be interested in knowing just HOW those are supposed to be accessed by anyone with experience. PS - still impressive how fast an 3/4" line can dump 40 gallons of hydraulic fluid.