Wicksteed Saw question.

Some friends have bought an old Wicksteed Saw. The unit has an Hydraulic lift unit painted red with oil retained in the Annulus of the cylinder.
There is a rotating lever on the top to control down feed and a rotary valve on the bottom to switch between down and up feed. When running and in up feed it feeds up very slowly. The question is is it likely to be the piston seal leaking or is the oil the wrong viscosity? I have seen 150 SAE mentioned on some saws. The oil in the cylinder is definitely thinner than that! It appears that the unit should switch off when in the top position does anyone have any information or pictures of what the original electrical control was like?
Thanks for the help
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