A Cook County jury awarded more than $4.2 million Thursday to a man who was electrocuted while replacing a light bulb on a lamppost at Arlington International Racecourse.The award was reduced to $2.7 million when jurors found plaintiff Michael Schaller 35 percent negligent following a nine-day trial before Circuit Judge Joan E. Powell.On April 22, 2014, Schaller, then 47, was working as a union electrician helping the in-house crew ready the Arlington Heights racetrack — formerly known as Arlington Park — for …