4 Wheel Drive/SUVs: transmission sticks in low, toy 4x4, valve body

Question
1985 toy 4x4 19 pan screws, after warming up 1/2 hour or so, tranny wants to stay in low or shift to neutral, have changed filter fluid shift sensors (2), and put in lucas, anything else I can do or put in, say if governor is sticking?

Answer
Sometimes it is cheaper to just rebuild it rather than keep putting costly additives and sensors over and over. The small things that don't fix it can add up to the cost of just rebuilding it in the first place. Sounds to me like something is sticking in the valve body and it is best to rebuild it if thats the case

Matt