1981-82 Honda GL500 Front Master Cylinder Repair Kit ~ Replaces Honda OEM 45530-MA4-671

I offered the wrong part to start with. I'm a goldwing newbie. Work on lots of cars, but bikes are fairly new. Anyway, working on my gl500 fixer-upper, I ordered parts for the interstate version of the master cylinder by accident. Larger bore for dual disc front brakes I guess. Anywho, Goldwing parts, which have shipped everything at no extra charge so far, is quite happy to take them back. I ordered the right parts and they fit well. Only problem, I believe the balancing hole is plugged up. Brake fluid won't drain down into the cylinder bore. The big hole is clear though and I can't figure out why the fluid won't go down through that hole. I removed the banjo bolt to make sure it wasn't the line and nothing coming out. If you guys can help me figure this out, would really be icing on the cake for me.