I replaced the blade on a Black & Decker electrical lawn mower. Now it makes excessive noise upon starting it and shutting off. There is also a burning smell when I turn it off. Should I have also replaced the rubber insulater washer that goes on before the blade nut? I doubt that is causing the noise.

If it is making excessive noise I bet it is vibrating as well. I suspect that the blade was not seated properly. As for the burning smell, you will just have to look around and see what the problem is