1967 Satellite replace front wheel cylinder

Hi guys i am in the process of replacing my two front wheel cylinders, My issue is one of the bolt heads is obstructed and cannot not be accessed by a wrench or a socket, To try and get better access i loosened the four nuts holding the backing plate, no movement, i placed a jack near the wheel to take weight off of the shocks just in case it was binding the bolts, what am i missing? something is holding the plate tightly in position, also any other ideas on how to remove the obstructed wheel cylinder bolt. pete
Author: sendust