I have a 1999 S10 4x4 and when i shift it from 2 wheel high to 4 wheel high it shifts instantly but will not shift back from 4 high to 2 high.The only way it will shift back is , you have to stop and put it into neutral or reverse , try and shift it into 4 wheel low and then to 2 wheel high?

Put in new switch on dash and a used shifter motor worked for short time now back to same problem!

Any suggestions?