Good day

I have this Toyota 03-fd35 and the hydraulic cylinder for the steering started leaking my guys removed the cylinder and I replaced the seals and fitted the cylinder back.
When the forklift wheels are off the ground and turn the steering wheel the wheels move side to side on there own with the smallest touch. Once I lower the wheels back to the ground and I try steer the steering is extremely hard.

Is there anyone that can assist me on where to look or where the problem could lie