Snapper Rear Engine Mower blade wont engage!

Hi, I have a Snapper Rear Riding Mower M281019BE w/ B&S 10hp. Yesterday I must have hit a rock and my blade has stopped turning. When I engage, all belts are driving normal etc but the blade does not turn. However, now I can turn my blade freely by hand without resistance as if it is no longer turned by the spindle. It is very loose, so loose I can simply tap the end of the blade and will fully rotate several times until the momentum is longer there. I looked at the spindle assembly parts diagram 'Snapper 7600138YP' to determine if there is keying from the spindle to the blade and I have not identified it or the part to be the root cause. Can anyone help determine which part is broken or even how to attempt the repair ?

 

First thing I would look at is is the nut tight on the bottom?

 

Stand it on end and start taking it apart, when something falls off you have found what was broke, I think the pulley is keyed, hold the pulley and see if the spindle still turns. Have a good one. Geo

 

I took a closer look at it, it looks almost like the nut at the bottom is within the blade holder. As though part 7 isnt there...

 

Number 9 is threaded to fit on shaft number 11. I have seen this part strip and allow the blade to spin like that. If it's not that, I'd suspect the pulley is no longer engaged to the shaft.

 

Thanks everyone for the input, this is a great forum and I appreciate the help!
Pete