Case 850k pops into neutral and parking brake engages randomly.

Hi all, first post here. I’ve got a 2006 case 850k that started randomly popping into neutral, parking brake engages and the the yellow gear light comes on. This happens randomly, on flats, hills, forward and reverse. The only consistent thing is that it will run fine for about 5min, then it will suddenly happen and then it will continue to happen every 1 or 2 feet of travel. Maybe as soon as the hydraulic fluid gets warm. I had a case mechanic come look at it, he thought it was the parking brake solenoid, and I replaced that. Well, it still happens, just better… I have searched forums, and googled this as far as I can. No answers coming up. It seems like it thinks something dangerous is happening and trying to stop the dozer as fast as it can. A safety feature. All the relays were replaced last year. Any thoughts as to what this might be? I’m on a job and having this machine available would be great. thanks in advance, -Kaleb