I saw that there was a complaint about the transmission kicking out on a 5130. I had the same problem for years, then I replaced the switch on the reverse and forward lever on the steering column and the transmission has never kicked out since.
Mine would stop when I hit a bump or was just driving down the road. It is a totally different tractor since changing the switch. The switch is like a heavy toggle switch that is maybe around $50.00.
Don