Valve cover plug

[PhoenixRising01]

There is a black rubber plug inserted in the top front of my right side valve cover. I've got a breather on the same comer toward the rear. I've noticed blow by, with oil collecting on the manifold and carb directly opposite the rubber plug. So, being the investigative genius that I am, I removed the rubber plug. It was just sitting there no pressure at all require3d. I wasn't aware that they came with different diameters. Now what to I do? This is not a screw in.