Glad I saw this!

Pulled mine out of winter storage yesterday and the brake pedal is basically dead for the first 75% of travel. Catches at the end and stops fine after that but driving in traffic is a dicey experience. I too assumed master cylinder but there was no signs of any leakage (I parked it over a big sheet of craft paper in November), brake fluid bottle was exactly halfway between min and max. Brakes were perfectly fine when I put the car away last fall.

I'll try the suggested vacuum bleed off.