Powersteering stiff

Ok guys i’ve done about three days research and still cant see why my steering is like this. My car is 89 ka24e 240sx, and i have a problem with the powersteering. My steering is stiff not as if the car was off, but stiff. I dont know what to do. I know im getting some powersteering because when u start the car the steering is a bit easier than when the car is off, but is still stiff. Please help me.

forgot to say resevoir is full.

maybe the power steering pump isnt doing the job. try checking for leaks or damage

is there anything such as a clogged ps line?

mabey you have a kinked line

how much would a belt belt help the situation?

I fixed the problem. Seemed as though the fluid was either the wrong type, or needed a flush. I simply spotted my dads 4L jug of atf dexron 3 fluid, and then opened the banjo bolt and ps resevoir. Then turned the wheel lock to lock to drain the fluid. then refilled with new fluid, and now its perfectly fine.