Black ball like motor very hot

"Unplug the unit before attempting any servicing" The "Black Ball" is the compressor. If it's excessively hot it is because it is being overworked. There should be a small fan next to it to circulate air past it and the condenser coils beneath the box. Make sure the fan is running, removing any obstruction to the contrary such as a dead mouse or excessive dust. If the fan doesn't run because it doesn't turn free as in lack of lubrication, try a spritz of light oil such as WD-40 on the shaft. While you're there, be sure to clean the dust from the coils under the box. The system (read "Black Ball") and the coils will overheat if they are insulated by excessive dust or if the dust prohibits airflow.