So yeah. That probably has been contributing to the whole not-stopping thing.
I put a bit of brake fluid in the master cylinder, which was bone dry by the way, and it all immediately dribbled out of one of the myriad lines coming out of the horrifying block behind the gas tank.
BUT none of the calipers are seized which is a plus. The calper rotor and pads on the right side are brand new, but I'm still inclined to replace them so I have brand new brakes of the same kind all the way around.
I put the 16" slicers back on too.