mrbob,
not sure on this one , due to the type of lift system on this unit.
you might want to contact the princeton dealer in your area and see if they can tell you. On most normal forklift hydraulic systems the velocity fuse is located inside the rod at the base where the packing gland is.
Your unit has a positive displacement system that allows the lift cylinders to raise and lower under pressure allowing it to lift and lower the load under pressure. Works very similar to how the tilt circuit works. Unlike the usual forklift hydraulic systems that are gravity lower cylinders.
The only two places i've ever seen velocity fuses are either in the base of the cylinder rod itself or is inside the fitting adapter at the base of the cylinder where the hydraulic line connects.
PAPE HAWAIIAN LIFT TRUCK is a dealer in hawaii, maybe they can answer that question for you? if they are willing that is.
There could also be a solenoid 'holding valve' on this system inside the control valve or in a manifold block.
Like i said, you should contact your local dealer on this.