same problem as you mate.i did my head gasket last year i put a cometic one on.earlier on this year it started using water,but no leaks.i whipped the head of and the gasket was fine.i had the block flat checked and it was warped.so now im doing a build.both surfaces have to be perfect to use a cometic gasket.so my advice would be to get your block checked out.my gasket didnt look like it would ever make a good enough seal again,and that was cometic.so personally i dont think they are re usable.although there are probably a lot of people on here who will disagree.i rang the guy at cometic and he was very helpfull.hope this helps.