A quick video installing/replacing crankcase/crankshaft/bottom end seals on a Polaris 250 Trail Boss. The video explains symptoms of leaking case seals, some things to listen for, check with spraying fuel around the seal, etc. In the end it runs great! Great replacement video. Similar method is used on 350 and 400 2 strokes: Trail Blazer, Big Boss, Xplorer, Scrambler.