I have a 2001 s10 blazer 4x4. The 4x4 had quit working and I got to checking everything and found out the cable wasn't pulling the differential in gear. I tried squeezing the vacuum actuator more but it wouldn't help. I pulled the shifter loose from the differential and checked it then put it back on and everything started working just fine. a few days later I tried to use it again and the differential won't shift again. pulling on the cable doesn't help but I'm going to try pulling the cable and shifter completely off the differential and see if anything is wrong. Could the shifter inside the differential be sticking?