Did I miss something?

Sorry you missed my point. What I was trying to say is, you don't want residual valves in a disk system, BUT THAT THEY WILL NOT cause this problem.

See post 6


residual valve in the Master?

That won't do it.

Did you change the master? If the stroke on the linkage is wrong, the master piston(s) won't return and will lock up the brakes