It isnt too bad out of flat now, I've been slowly working it here and there with a flattening stone, I think it's responding as well as one can expect a stone this hard to.

I try to avoid anything that looks like it may have been used as a hockey puck. But photos can be deceiving, so I view anything purchased off there to be a gamble, and I try to 'hedge my bets' so they aren't a loss. So far the strategy has paid off.