Locked Caliper

So, I've developed a problem with a locked front caliper. I have the master cylinder and front caliper off the bike and am preparing for a rebuild. The rear is a drum brake and I already put new shoes on and cleaned up the rest of the rear system.

The inside of the master and caliper (after I popped the piston out) were pretty crappy looking with some nasty looking crud, and I'm sure that's a major contributing factor.

I do have a question. At the bottom of the master there are two holes. One I assume is for allowing fluid from the reservoir to the piston to the system. The second is ... a return? a vent? The second hold in mine appears to be plugged. Should it be open to the piston? Should it be a large an opening as the other hole?

As always, thanks for everyone's help.

yes both holes should be open in the master cyl.
if the caliper is froze, fill it with pb plaster and let it sit, close the bleader and use a rubber tipped air gun, hold it tight and blast away, NOTE: keep fingers away from the piston, and cover it with rags, if not you will not like the results, I know this first hand

From m/c reservoir to piston bore, the supply port is the larger and the relief port is pin-hole size.

As signature mentions Frankenbike, are we dealing with stock m/c and caliper?

Thanks. Yes everthing is stock.