Thanks for your reply Carl. I hope he's just ignorant as well. I never questioned why he had it planed as I figured that was water under the bridge. I checked it before I listed it and it showed no signs of warping or cracks. I figured it was a simple case of some scotch-brite or wire wheel work, gaskets, and then following a procedure like you detailed or I detailed above to install and get'er on down the road...
Either way it's a less than ideal situation! That is for sure.
I believe in the 'customer is always right' theory... It's just that every so often they're not. It's trying to determine if they are wrong because of ignorance or deceit that is the tricky thing. In this situation, I don't feel like he should get off free for either one. If he roached a manifold out of ignorance, then that's a painful lesson he should have to learn. If he's being deceitful then he sure as hell shouldn't get to bend me over. Either way, at this point, if what ebay customer service told me is true it's going to be up to me to take the gamble on negative feedback and appealing it, because I will not be made to accept the return request because he has already had it physically altered.