Working on a 1995 NH RG140, will move about a foot in forward or reverse but thats all. How do you get the trouble codes if any to show up ? Trans is full of proper fluid per manual.
Do you know or can you find out what transmission it has? Do you have a manual? If there's electronics involved there's usually a way to get codes. The problem on here is not many members are familiar with your machine. I'd look for a manual(s) online and/or call a NH dealer.