By James B. Kelleher CHICAGO Tue Sep 16, 2014 2:48am EDT (Reuters) – Farm equipment makers insist the sales slump they face this year because of lower crop prices and farm incomes will be short-lived. Yet there are signs the downturn may last longer than tractor and harvester makers, including Deere & Co, are letting on and the pain could persist long after corn, soybean and wheat prices rebound. Farmers and analysts say the elimination […]