Just bought this machine 2 weeks ago. "99" 1700 hours. Owned by rental Co. Hauling dirt with it every day. Yesterday I was coming down a steep incline empty and felt a medium bump to the rear as I went over about an 8 inch drop. Engine immediately quit and the brakes locked up. Changed out some bad looking fuses and later it started. Now I see the green lights on the control box for the first time. The traction light flashes and the overide switch is dead. About every third start (while movin' throttle all the way a couple of times)the light will steady, switch will click when pressed, and the machine will move. Within the next minute the brakes will lock up. Verified about 10 times. Raised the cab and appears to be 2 solinoids, the rear one looks old and someone has rounded the head of the bolt but couldn't get it off, the forward valve looks new. What are the possible problems??? Does this bolt go through the solinoid, if I drill or grind the head can I replace it?