Power steering rack

I just purchased a 86 laser turbo, it has power assisted rack and pinion and the wheel is stiff but when your turning it will at an instance become super easy causing over steer and then will tighten up again. Not familiar with these old systems, any help would be appreciated. Im not sure if it's the rack going bad, the pump going bad, or if the belt could be to lose or???

1st check the belt. Your rack may have "morning sickness". One 12oz bottle of this is the cure: http://lucasoil.com/products/problem...ring-stop-leak

Check the fluid. I've found that most of the time if the rack is giving me a hard time it just needs some fluid again.