Someone gave me this hone. I have used it without lubrication, but I beleive it was clogged before.

It's a Swaty hone.

I want to be able to use it.

How do I find out if oil was used or water?
How do I clean it off? I have some hard spyderco stainless steel clogged in there.
How do I make it flat again? I think it has an "pit" in the middle.

Thanks