Getting to the bottom of my 'blade won't stay raised' problem (from  5 years ago btw) and have found a stuck valve in the valve assembly that may be the problem. But, while the tank is open and to complement the newly rodded and rebuilt old style hydraulic cylinders, thinking that I will rebuild the hydraulic pump also. 
So here's my quick question - will the hydraulic pump simply pull forward out of the tank? and, will that entail any loosening of fittings behind the tank where where the drive for the pump attaches? 
thanks for any replies, 
yellerc@

Hey neil, that sounds about right from what I see in the manual. Hoping that the splines work that way; it does make sense.
Cartridges are N/A of course, but hopeful that the rebuild kit with the vanes will give me all the potential that is there. Also curious about the bearings so its all worth a looksee in my opinion.
Thanks for the reply!
yellerc@

I think the Cat pump for the D6 hardnose is a bit bigger than most of us want to handle by hand.


Some times it helps to get all the groves and such smoothed out of the end plates. Then shimming so you still have a good fit to not let oil get away between the gear and end plates. If you are lucky you can just turn the end plate over to a new surface.

Very good to hear that, guys. Planning on removing and inspecting now. Had one cartridge found for $2K so won't be going that route. Wowza !
Will check to see what the insides look like and replace seals and hopefully no scoring on the inside of the cartridge. Buddy mentioned Hydradyne in LA. as a possible rebuilder if it is really tough looking.
Immediate problem is a stuck valve on the valve assembly so will start a new thread with pictures, cause everybody likes pictures.....

the vane pumps cat used were Vickers brand which became part of Eaton hydraulics. you might be able to get after market parts via a local hydraulics joint. yes anything that is for hydraulics you would think by the prices was 24ct gold plated.

Welp, the pump is out and the cartridge is in very sad shape. Lots of scoring and this is likely the root cause of my blade refusing to stay elevated.
Removed the front cover of the pump and slid the cartridge out before the body of the pump. Much lighter this way than as one piece.
The bearings need replacing, but the biggie will be the cartridge replacement. Probably put up a wanted thread.

The pump should have no bearing on the blade staying up. The pump provides power for the movement, but valve should hold the oil once it has moved the ram. So oil is leaking around the packing on the piston on the rod in the hydraulic ram or is leaking at the valve.

Thats really good news, Ray.
The cylinders have been re rodded and packed recently so perhaps my valve was the problem; which means the pump will work better than it looks.
Maybe if I reassemble with the valve(now) freed up, it will be operable. One thing is that the blade would lift the front of the machine, but if memory serves, it would not stay up....