I have a Snapper self-propelled walk behind mower with the B&S 7.0 hp OHV engine. After resolving some fuel system problems, I discovered when cutting that I need a new blade. The blade is like the one pictured below with the splits on the ends. Do I have to replace it with one just like it? They seem to cost about twice as much as a regular blade. What does the irregularly shaped end of the blade do that a regular straight shaft blade doesn't do? Can I replace it with a regular blade without damaging the engine?