I had to replace the fuel pump on my blazer. All went well and it runs perfectly. A problem arose several weeks later when I needed the 4 wd.---Nothing. I removed the battery and noticed the diaphragm was fully collaspsed. First thought was the vacuum had not released and was holding the cable in the fully extended position. Removed the diaphragm and it went back to it's original position but the cable would not retract. I can pull the cable out another 3/4 of an inch and it will retract back into the diff. but it is much too long to attach to the diaphragm. Four button controls---just blink. Any ideas will be appreciated.