Brake Master Cylinder leaking problem.

I've got the same issue, after a good romp thru some twisties, no rear brakes. I also filed the top of the MC body and still leaks, even bent the "wire" snap a little to hold more pressure on the lid..still leaks, better but still leaks..never even thought it would be soooo simple (walks outside to check). Maybe I shouldn't park nose down the driveway anymore either.