C15A brakes jamming

[motto]

If it was a hydraulic problem then opening the bleeder at the wheel cylinder would release the brakes on that wheel at least whether the blockage was caused by a master cylinder fault or a restricted hose.
Yes, it is possible for components to corrode over time even if assembled with rubber grease. A lot depends on the quality of the grease and atmospherics.
I don't know the exact brake set up that is causing problems here but running the adjustment out and back may do nothing to retract the pistons.

David