Hi all. I have an old D125 that I bought new in 2007. The deck a big enough hole in it now that it was affecting the grass discharge. I bought a new deck and put it on, adjusted it best I can. I measured the blade height, it looks like it is 2" when the leaver in in the 2 slot. The problem I have is that when the mower is running and the blades turned off, then just raise the deck all the way up, the blades start up. What would cause this?