If the Power Steering box is leaking below the adjusting nut, it is like that the seal is faulty. Replace the seal on the power steering box.
check the power steering and brakes "mini-radiator" that hangs below the radiator. usually gets hit with all the weather, can be replaced easily.
Power steering hoses Pump Steering rack
Check power steering belt, check power steering pump, check rack for leaks
The problem is probably in the steering gear. Clogged passages in steering gear. Leaks in steering gear.
could be several places, power steering hose, rack and pinion (or steering gear box) or power steering pump.
Hard power steering means there is little to no fluid left in the system. The power steering system should be flushed and checked for leaks.
The belt is tightened with an adjusting screw.
it is on the steering column below the steering wheel
You can, but you risk overheating your power steering pump and rack. Not good for the seals and they will leak for sure after a while.
Usually the leaks are at the high pressure line or the return line of the power steering pump. Tighten all the lines at the pump.
Synthetic power steering fluid from the dealer only. Do NOT mix drugstore power steering fluid, ATF, or non-synthetic fluid in your steering system. Damage to the seals/gaskets could result in leaks.
The most common reason for power steer failure is fluid leaks. On power steering pump, you should check behind p/s pulley for leak at the shaft. On the rack and pinion(steering gear) check rubber boots at both ends and check for leaks where steering shaft is connected to rack and pinion input shaft. Check pressure hose at crimp fittings for leaks.