I just bought this 5 year old 33 inch snapper 12 horse power I removed the blade because one end was contacting the deck. I bought a new blade, but it has the same problem. So now I'm thinking it must be th block bolted to the pully shaft on which the blade is bolted. I'm assuming the nut holding the block onto the shaft is a standard top to the left to unscrew? I'm having no luck breaking it loose Does anyone know for shure?