I have a really stupid question. I went to sharpen the blades, and measured the nut that holds the blade to the crossbar. I measured 1 -5/8". So, I went to Sears and purchased the socket. I get home, and try the new socket out. It seems really tight! I cleaned the nut off, and still it seems tight. Is this nut 1-11/16" ?? Anyway, I meaured it again, and I measure 1-5/8". What am I doing wrong? I don't want to spend another 20 bucks and then find out it is metric.

Anyone know the right size? The manual does not have the size listed.