Test fit the plug just to make sure it's the right one. If it doesn't slip in the cavity don't force it yet. Clean the cavity with brake clean and dry the cavity. I used silicone sealer around the the of the plug. install it with the dish outward and use the ball end of a ball peen hammer (and hit the other eng with another hammer) or use a 1/2" extension to dent the center and expand the plug. Make sure you let it sit a while or overnight so the sealer sets up. Someone may chime in with a different process but the outcome is the same.
