4x4 not working properly on 2003 Chevrolet Silverado 1500

have put new actuator on my 4x4 2003 Silverado manual tranny manual 4x4 when putting in four wheel drive 4x4 low works 4x4 high hardly ever sometimes light works and 4x4 also put another new actuator on worked 30 min. then same thing mechanic said he thought might be modulator valve in transfer case help help

1 answer 1 comment
how does the fluid look? burn't or metal in fluid?
mechanic hasn't looked at the fluid yet putting it on computer tomorrow