Bobcat excavator blade: what am I missing?

[VernLPoole]

I have a Bobcat 337 and ever since I got it, the blade has not locked down so that I can use it for leverage when digging/lifting. I finally managed to find enough fittings that I could put together a hand pump/pressure gauge so I could test the port relief valve, thinking that would be the problem. I hooked up my test rig, but could not get *any* pressure to register. I tightened the port relief adjustment screw as far as I dared, with no difference. I can't make sense of it, because it is definitely holding *some* pressure, because if I lift the machine with the blade and then let the handle return to the neutral position, it takes maybe 15 seconds for the machine to drop back down, as opposed to for instance the "float" position where the machine would immediately slam to the ground!
I inspected the mechanical linkage from control lever to spool, and as much as I can see, it all looks OK: the linkage doesn't seem to be exerting force on the spool when lever is in neutral position. So what else could I be missing?
Oh, and now I have the additional problem that I have pumped the hand pump empty and can't figure out how to replace the oil! Anyone have experience with this type of pump? (I've attached some lousy pictures, taken through a film of hydraulic fluid on my phone lens, no doubt!) Is the allen screw on the business end likely to be the fill port? Or do I unscrew the knurled cap on the other end? The allen plug seems to be tightened to a dangerous degree and/or loctited... I leaned on it till I feared I would break my allen tool and it didn't give.
Any thoughts on either the blade issue or refilling the pump would be much appreciated: I am stumped all around!

 

[LD1]

Where did you hook hand pump to?

(Be careful with that hand pump. Most of those are capable of 10,000 psi which is well above what the machine is capable of).

Were did you have it hooked. Did you isolate the cylinder? Or just tee it in?

I am guessing you have leakage back through the spool valve itself unless you have oil leaking from the cylinder or hoses themselves and making a puddle on the ground.

No idea from the blurry pics where to fill the oil. Those pumps are normally self contained with the attachments....and adding oil is not a normal thing with a porta-power