I cant get my truck out of 4 wheel drive

I cant get my truck out of 4 wheel drive. It has the automatic push button for 4 wheel high and 2wheel low. It should come out of 4 wheel on the fly if I depress the 4 wheel button again but it dont. It does shift from 4 wheel low to 4 wheel high in neutral. I have replaced 2 vacuum lines that run from the actuator under the battery and one to the main vac I think, they where dry rotted pretty bad.I also replaced the vacuum switch on the transfer case, I took it out and the ball at the end did not move at all (the new one did), so it need to be replace too I guess.I changed the fluid in the transfer case and screened for shavings. None found. Is there a common thing that wont allow it to engage and disengage, that I can check?Is there a manual way to disengage it at the transfer case?Im going to look at the thing I believe to be the actuator thats under the battery tomorrow. Can some one tell me what to look for in a good or bad actuator or any other thoughts. Thank you for your time.