John Deere LT160 not start, battery is fully charged (100%). ?

My son was using the tractor and it was running fine. At one point when he went to restart the engine it would crank but not start. I jumped it and it started. Eventually it got to the point where it wouldn't crank and now it only clicks when I turn the ignition key and won't crank when I attempt to jump it. For whatever the reason, the (condenser?) at the bottom of the carburetor gets quite hot. The solenoid coming off the battery seems to have activity when the ignition key is turned, it feels as if it is operating...but when a volt meter was put on the solenoid it showed 12 volts going to the solenoid but zero volts exiting.

Thanks,

Rob