This has been diacussed many, many times....pretty simple fix, no rocket science involved.
Just buy a new accumulator with a schraeder valve from surplus center or wherever that matches or is larger then the capacity listed on the original, mount it to the back of the seat and have a hydraulic hose made up to connect the two.
You'll need to adjust the pressure in the accumulator to suit your needs...bleed it off or inflate with an air compressor as needed. The new accumulator will probably have around 2500 psi and you'll only need around 100 or so depending on operator weight.