The spark plug tube seals are the fix. There is a writeup about in the DIY section.

The upper seals are more common for failure and you can get a felpro gasket set with the valve cover and spark plug tube seals for pretty cheap.

Pay attention to the orientation of the original upper gaskets (heads vs tails face on the new gaskets). I know on my EX model, it was kind of counter intuitive on what side seats against the valve cover until I realized how they sealed.

You will also need to pick up some permatex grey (equivalent to HondaBond) to seal the two corners of the valve cover gasket against the valve cover where the cover arches around the cam sprocket.