4wd not working

[idontknow]

I can't figure this out. I push the button, nothing happens. Push it while in revearse, 4hi and lo blink but don't stay on. Changed the transfer case switch, no help. Found hole in vacuum line at the actuator near the actuator under the battery. Replaced it and it worked fine until I turned off the truck and started it later on. Now it is doing the same thing. What is going on???? What else can I try???

[bigbusiness]

I have the same problem in my 94 blazer. I have no idea how the system works so i haven't tried anything yet, but if anyone could offer some help it would be greatly appreciated,