Ned - I don't have a 124 manual to check out, but generally the steel ball is used to plug an oil passage after it is drilled. You can't always machine a "dead end" hole, so they drill all the way through and then plug the openings that should end up closed. When you are trying to clean out any accumulated debis, you want to open the passages back up for access to get proper cleaning and verification of cleanliness by inspection performed by looking through the hole and/or blowing air through it.
Barry >What does the steel ball do in the main oil gallery? >Why would you want to knock it out?
