I have a M8580. Was driving in road gear when all of a sudden both front wheels completely locked up and shut down the tractor! After trying several minutes to get off highway I had to put tractor in reverse. Tires would then turn for a few hundred feet and then completely locked up again. After backing up a few feet they would turn again. I had to do the for several miles to get to a safe place. High/low range worked fine, 4wd lever works ok. Has anyone else had this issue