also check all the vacuum lines between the actuator and t-case, and up to the engine. the hoses are fairly shitty rubber and can degrade over time causing a leak. my 95 had a similar issue so i had to replace all the vacuum lines for the 4x4. they crumbled apart in my hands when i took them out.
"I don't have pet peeves, i have major psychotic fucking hatreds" -George Carlin