I've got a Snapper 52" hydro walkbehind mower, and about 2 weeks ago, in the middle of mowing I had stopped to empty the grass bags, turned on the PTO and heard a loud scraping sound and saw that the end deck spindle wasn't rotating, so I loaded it back on the trailer, and finished up with a backup mower.
That night, I take off the electric clutch, notice that the clearance was way out of spec (I hadn't adjusted it or even checked it since buying the Snapper 3-4 years ago), adjust the clearance, reinstall it, fire it up, turn on the PTO and hear the same loud scraping sound and end deck spindle doesn't rotate.
So, my diagnosis is failed electric clutch, likely from not being adjusted, so I order another one, which came in today.
So, take off the old electric clutch, install the new one, and now I get to putting on the pto to deck belt (there's a separate deck belt). I get the belt on the pto first, and then it's kind of awkward, with the bags hanging in the way, the deck tilted up, and reaching over (it's on a trailer and I'm standing on the ground), and at this point, while struggling to get the belt on, I notice that the front deck pulley wobbled just a bit.
Take the belt off, and find that the bolt through the spindle had come loose, and the 12-point hex in the spindle & pulley were mostly worn away.
So, most likely (as I didn't really feel like taking everything apart), the original electric clutch was just fine, perhaps better after being adjusted, and the actual problem was the loose bolt..
Now to get a $50 pulley and swap one of the end spindles with the center one...