No locked wheel cylinders.

Combo valve piston still centered.

I checked and adjusted pedal free play and rear drums.

Booster check valve I think is OK. I can't blow air in but can suck air out. As far as it holding pressure, I don't know. But I know it did work at one time and the only thing I did when it quit working was vacuum bleed the rear brakes.

Revving the engine to 2000-3000 rpm then pressing the brake pedal doesn't seem to have any affect. But my vacuum gage died so I don't know how much vacuum I'm getting.

Brake pedal still hard as a rock and doesn't stop very well.

I'll try the 1" master cylinder this weekend.