take it for free and lose.
im not gonna read all the BS back and forth. when you buy something and agree then its a done deal UNLESS a warranty is implied. why didnt the pan come off the day you bought it? thats your fault. I just sold my engine and I would have done anything the seller wanted to make him happy. but when he left with the engine it was his. he said deal and that was it.
learn from your mistakes.