OK lesson learned. I won't leave old cans of brake fluid around.

Now, I just removed the old MC. I got a new MC and a complete MC/reservoir/booster kit from the junkyard. I just found out that the JY booster is slightly smaller in diameter and that the MC attached to it has 3 lines connected to it while the one on the car has 2 lines and the extra port plugged. It must be from an earlier model...

Against all odds, I didn't find swollen seals on the MC that was on the car. However, it was stuck to the booster with vacuum. I could pull on it to remove, but it would get sucked back. I had to undo the vacuum line connection to pressurize the booster to free it. I changed the check valve last time, arrow pointed towards the engine.

The booster has oil in it. It holds vacuum but it seems to leak under it. I'll remove it to inspect closer. How can I make sure it's good? Last time I drove the car, the brakes felt good, but on the few last stops they started pulsing? I doesn't seem like it's related? No external leak around the MC was visible... I'm really puzzled here!