Any one who can help me with a failure on my Fendt 939, recalled model 6769. The tractor seams to restart every 15-30 sec and needs to be repaired every single time. I have changed the mainbord but no positive effect. I am running this tractor on a after market battery, https://www.youtube.com/watch?v=hVt1xwehJ7E. A battery that runns just perfect in my John Deere 8430T, model 6762.