Regarding reaming out the lead tubing, this is a little tricky. Most simply put, the I.D. of the lead tubing is smaller than the O.D. of the brass tubing insert. So, the lead tubing it has to be carefully drilled out to a larger diameter where it passes through the valve block mounting board. I do the job with a manual hand held drill (not an electric drill). The drill bit I use is 0.002" larger than the O.D. of the brass insert. I secure a depth limiter (a brass collar with a set screw) on the bit so I don't accidentally drill the hole too deeply. Here's why: As you know, the lead tubing bends at nearly a 90 degree angle on the back side of the mounting board. If the hole is accidentally drilled too deep, it will poke a hole in the lead tubing. In fact, I only drill out the lead tubing to a depth of 1/2".

What's interesting is how easy it is to drill out the tubing. Basically, you're not drilling lead but rather lead oxide - which is quite a bit softer than the lead. In a sense, you're not really drilling out the lead but rather cleaning off the corrosion that has accumulated over the past eighty plus years. Once this is done, I paint on a layer of Phenoseal around one end of the insert and gently work it into the hole. To insure that each insert goes in the same exact distance, I place a 1/2" metal block next to the insert and gently tap the insert to its final 'resting point'. Then I let the Phenoseal dry thoroughly. Once it's dry, I apply a bead of Phenoseal around the base of each insert with an eye dropper to insure a 100% air tight seal.