An electrical problem is likely to blame for sparking Monday’s deadly grain elevator explosion in Union Mills, according to fire investigators. Two motors apparently overheated and caused the silo to blow up, killing 67-year-old James Swank, who was at the top of the structure when it blew Monday afternoon and fell to his death. The fire was contained to the silo, and no other injuries were reported. The fire rekindled Tuesday night, and some grain was still smoldering Wednesday. Officials with the Bureau of Alcohol, Tobacco, Firearms and Explosives and State Fire Marshal’s Office were called in to investigate.