awd issue 1997 500

Hi, new b here I have a question that has puzzled me for days. I have a 1997 polaris 500 4×4 all seems to work ok except I cant get the front left wheel to disengauge when I want to be in 2w. Have I got a bad armiture plate I’ve had it apart 3 or 4 times cant find the problem. Sometimes it will disengauge then go back into 4×4 it is a real bear to deal with! Dont want to take it somewhere to get a simple fix done if I can help it.. Thank for any advice or help