John Deere LA115

Yesterday I'm laying in my driveway changing my oil & I hear my neighbor try again & again to start his riding mower. It sounds to me like the starter is free spinning so I walk over. Turns out the flywheel [U]is[/U] spinning but way too freely--no compression. Pull the plug & can only see the top of one valve--but at least it's working. No puff coming out the plug hole or the muffler. Pull the head & verify the piston isn't moving. I should say this is an old Wheel Horse mower with cast iron splash lubricated 12HP Kohler. I'm told it simply quit while mowing with no warning or other symptoms. The part I'm puzzled about is how the crank can spin and not hit anything. The piston is halfway down the cylinder & if I nudge it a little further it does get bumped by the crank. From this description what am I (or more likely HE) going to find when the case is separated? The only thing (to me) that explains the crank spinning without knocking from a flailing broke rod is if the rod cap broke off. At this point I'm just curious.

My generator is only producing 120v instead of 240v. Only half the 120v plugs work. Only one hot line instead of two working for the 4 prong plug. I could not locate a fuse burnt out, or anything else obvious. The brushes were worn, but have been replaced. Any thoughts or suggestions?