Okay so I have an lmm that the 4wd will not engage in. I am sure the transfercase is engaging and the front actuator is working as well. While I had the front actuator out I tried to manually engage the diff with a screw driver and it wouldn't budge. I also noticed that there was some diff oil where the actuator screws in. My thought is that maybe the shift collar or fork is broken? I'm just looking for any advice as to how to fix it or what else might be wrong. Thanks