Kohler Guys: Looking for Advice with Governor Gear Cover

Kohler Guys: Looking for Info on Re-Installing Welch Plug

I have a K321 series engine. There is a little cover about that size of a half-dollar, silver, and domed, on the outside of the engine. It is called a Welch plug or Welsh plug. Removing this plug will enable you to visually inspect the governor gear. I put one in a year ago, and it started leaking oil. I put in a new one today, and it leaks like a sieve. So where did I go wrong? I just hammered it in place with a big socket, dry. Are you supposed to use Permatex or some other gasket making material? I was kind of reluctant to use one of those silicone based gasket makers in case I have to remove it. I don't want any of those little particles falling into the block. So you've heard from the amateur. How do you pros do it? And yes, I am using new plugs when I put them in. Thanks.