[Healeys] Front disc brakes locking up after rebuild

[Ron Ray]

Folks,
 
After rebuilding the hydraulic system the front brakes do not release.  If
the bleed screw is loosened, they do release.
The rear brakes do not lock up
 
All rubber hoses were replaced.
All original steel brake lines were clean with air pressure.
The connector valve on the passenger side was removed and cleaned with air
pressure.
The caliber pistons can be moved by hand when they are off the car.
 
When the front brakes lock up, the master cylinder piston does not return to
the full "forward:" position.
 
Any suggestions would be greatly appreciated.
 
Thanks  
   Ron