A white lithium grease works well for lube on o rings & sharp edges, and it then dissolves in oil well too.
I've been listening to the whine of that pump for over a decade now, I know how it should sound when running at optium speed.
I'm curious to see what your cyl cycle speed is like when you do tune the pump to 6000rpm (est)? I've been thinking for awhile of installing a Leimbach pump & valves into this HK hoe I have with the oem cyls.
No need to get your hoe dirty to measure the ground level reach... while on the kitchen floor, measure from the center point of the house pivot to the very tip of your bucket with the arm fully stretched out along the floor... my 850 is 1400mm, as an example.
I understand what you're saying, and yes it does take alot of hyd power to nearly level the stick, especially with a bucket full of dirt.. it's a negative leverage.
Your custom Mruder is taking shape nicely in just over a month.. your early pics of hacking & wacking & gobbs of expoxy widen my eyes with much WTFism!!!
Now I'm looking forward to seeing it in motion.
..especially with the snake in the same area.