jrdamien,

As posted by Tommy, the oil feed tube to the rocker arm was often crimped/cut (by people trying to get more oil into the rocker arm shaft, presumably). Cleaning the assembly should have been the first action, but crimping/sealing the feed-tube was much easier.

If you want to be bored with TMI, here is some information, illustrations, and photos of the various styles of "oil connectors" between the rocker arm shafts, 1937-1962.