When I replaced mine, it was a real pain to get out, and as you saw in my video that LittleCaesar linked to, I had to use the long pliers and channel locks to get it out. If you have already tried that to no avail, you might want to try cutting the old grommet with a razor blade in one or more spots to try to loosen it up a bit. Take caution not to drop any pieces down into the valve cover, though. Minuscule bits might not hurt anything, but I wouldn't take chances leaving a big chunk of old grommet down in there. It was a while ago, but I think it might have even taken two of us, one with the channel locks and one with the pliers, to pry the darn thing out. Good luck, it's not too bad as long as you work methodically and use force when necessary.