k1500 4wd not working properly

Ok so I own a 88 chevy k1500 and the 4wd dosent work properly. i have been having a hard time diagnosing the problem so i am hoping some1 will be able to help me out.

When shift lever is in the 4wd position, in either 4 hi or low, it doesen't always engage, or when shift lever is in 2wd the 4wd will engage and the front drive shaft will spin without being locked into 4wd

I have tested the actuator in the front differential, replaced the switch on the T-case and checked for power at the connections. I dont know were to go with it next any ideas on what it could be?

Sounds like you need to realign the shifter. Not sure what the exact procedure is on yours. what model transfer case do you have?