I have a MTD yard machine (MTD model 607) that I have owned from day 1. The other day I went to remove the blades and the entire bolt spun but the blade didn't move. I had the blade blocked as usual and used my 1/2 socket on a breaker bar that I use just for this purpose. I have removed the deck and cleaned it to get it ready for repairs. Before I get into things I thought I would ask your opinions on what to look for? Thanks all for your help.