The cap you have is an older repro cap. The hole you see is supposed to be the vent hole. The red material you see in the hole is caused by the fiber gasket that acts as the cap seal having shifted in position and now blocking the vent hole. This particular gasket can not be replaced as it is “sandwiched” in between the outer and inner cap when they are riveted together. You can easily drill through the gasket with a 1/8” drill bit through the “vent hole”. If you have a drill press. You can easily (carefully) also drill 1/8 holes, through the metal and through the red gasket, in 2more positions in a circle outboard of the center rivet. This can be done with a hand held electric drill as well, but the drill press allows more control over holding the cap while drilling the holes. And, NO, you don’t really take a chance that the drill will go through the outer cap and ruin it. Once you’re through the metal, you can quickly drill through the red gasket without going any further.
