[Mark in MT]

Good luck. It is tricky to get the plugs drilled out on center without getting into the cast iron. They can also be a bear to get swedged in so that they don't leak with out breaking the housings. What I do is to use wire and brake part cleaned to clean them, I use a small fiber optic on a flashlight to shine light down the passages to prove them open. If all else fails, then they get drilled.