LT1 Steering pump "knock"

[Lawrence]

I have a 94 LT1 in my Camaro that had a new steering pump on it when I bought it. When you turn the steering there is a knocking noise that seems to be coming from the pump that stops the moment you stop turning the wheel. If you grab hold of the pulley on the pump, you can slide it in and out about 1/4" or more and it makes the same noise as when the pump is running. Should I have forward and backward movement? Or does this sound like a broken pump or maybe a badly fitted pulley? (It's all stock)

[David Pozzi]

Some front to rear play is common, but 1/4" seems like more than I've ever seen.
I'd say perhaps 1/8" to 5/32" is more like it. I think that pump has a c clip at the rear end, it holds the impeller on, it may be gone or damaged.