After 3 seasons on the mower and 4 on the trimmer I decided to pull the plugs. They were easy enough to take out. 1. I just google it "spark plug 796112" but they had a letter 's' after the numbers, is that the same? Is that the way to find them just line up the numbers on the plugs? 2. (Sorry...this is awful) Do I clean the socket area out with anything? Do I put some grease on the threads before reinstall? (Sorry...haven't done it before). Appreciate advice/recommendations.