Sometimes the Eddy heads have an issue with the oil passage feeding to the rocker shaft not quite being drilled all the way through & leaves a burr that blocks the passage by about 50%.
I've also seen rockershafts that have little flaps of metal where the rockerarm oil hole is drilled through with a dull bit. You'll need to extract the end plugs to verify.
I also like to grind a little slot in the shaft where the oil comes up through the saddle bolt hole to give a better flow path for the oil.