I have a 97 blazer 4x4. 4wd worked fine last time I needed it, now it didnt work tonight. Started snowing on my way home from work. Put it in 4hi and it wasn't working, I was still spinning and slipping. Went to a parking lot near the house and drove around for a bit and the 4wd seemed like it would catch occasionaly and work for a few minutes then when I stopped and moved again it would go out. Got home and put the truck on jackstands, front axles are not moving in 4hi or 4lo. I pulled the vacuum line off the orb and it was holding pressure. Took a look at the actuator and it was compressed in like the 4wd should be on. When I switched over to 2wd the actuator did nothing. I could find no leaks in any of the lines but the actuator is staying engaged but the front axles are not moving. Any help would be great.