After rebuilding the lift cylinders on the one I worked on the problem continued, just like what you describe. Those lift cylinders have a lot less force trying to push the forks down, compared to up, due to losing the surface area the shaft takes up. Even at 2500psi the rollers all have to be good to get that heavy machine to lift up or there is friction and binding. Being outside and the road grime getting on these machines they need lots of greasing. Maybe you have a pressure problem but once I got the one roller turning again and lubed everything away it went.