I have a Briggs Intek 12.5hp on a Snapper RE. I use it on a slight hill an noticed over time it really struggled with going up the hill. I discovered the drive disk was covered with oil. I cleaned it up and kept mowing. It never got better, just worse so i stopped using it for 3-4 months. I went to pull crank it and oil slung all over the place. Engine sounded real good before this issue. I hoping just a seal. I plan on investigating more today. Any insight? Or expectation of what I might be getting into? I'm not a small engine guy, but i want to be, so I plan to give it a try.