Yeah, I agree with firebird on this one, as I had the same experience with the vacuum bleeder. The fit of the hose on the bleeder is critical, and the instructions on the one I used warned that a small trail of bubbles would be from thread leakage. The drilled out bleeder is a pretty slick idea, but I'd say you've got a bad master cylinder. Nothing else explains having a good pedal, working fine and then the pedal going soft. You've got an internal problem on the MC seals.