Black & Decker MM675 18" Lawn Hog Electric Mulching Mower

I have the above mower. I was mowing the awn when it started vibrating. I checked later and it appears the blade is loose. I can try to tighten it but it won't tighten and jsut keeps spinning. I do not have the user manual. Is there a specific way you would do this? It would be the same you would have to do to take the blade of or tighten it. Thanks.



Here is a link to a page that has the mower on it.

http://www.toolking.com/blackndecker/view.asp?id=1719