[PsYcHe]

Corroded disk on the inside sounds suspicious... Should be nice and clean there, I'd get someone to work the brake pedal while you look at the caliper, could be sticking.

The sensor it a bit tight to get out, a couple of light taps with a hammer to loosen any rust, then grab (carefully) with some big pliers or mole grips and see if you can get it to move.