No brakes or brake pressure?

Title says it all. Roomie's car, a disability conversion van, not professionally done. Took a while to figure out where they moved the ABS Control Module and Pump but managed to locate it. We tested for line leaks everywhere and I saw not one drop from all the peddle pumping. So, I went up top and checked the master cylinder for leaks, didn't see any other than the reservoir seam had a leak if slightly over-filled.

I'm assuming that since we have no brake pressure, the ABS Light hasn't indicated a problem, and no line leaks thus far I'm looking at a failed master cylinder. That sound right? I say this because over the last few months it's been gradual then all of a sudden, the other day she couldn't stop and slammed the car into the gate leading to the house, only damage I found was a torn apart steering rack boot on the passenger side which is a simple fix. Just wanted the thoughts of pro mechanics who deal with brake issues all the time. I'm not a pro mechanic but in the upper level of DIY home mechanics so I hold my own. I have several books of those 3rd Generation Chrysler Mini Vans, so I know how to remove the master cylinder. Isn't there a seal at the back of it that must be changed when replacing the one in the vehicle?