470's mechanical lubricator has a bronze steam manifold with four loops to heat the lubricating oil. One of the loops had a split from freeze damage, another had minor swelling from freezing. So, it went to Bob’s shop for repairs.
Both of these loops were removed and the unit glass bead blasted. This revealed that there are two plugs that seal the manifold passages. These plugs are where the drill entered the casting to make the passages that interconnect the steam loops. The 1/8” NPT plugs had been cut off flush.
Closer inspection revealed a problem…. Apparently in the distant past these plugs had been drilled out and replaced. When the drilling was performed, that back portion of the plug broke off and traveled deep into the passage. You can see it lodged in the hole feeding a loop. Completely blocked off. Decided the best course of action was to remove all the tubes, the plugs, re-drill the passages and ensure all was clear. Sure enough, the other plug had done the same thing elsewhere. Little to no steam could flow.