Blazer 4wd problems

I'm having some major problems with my 4wd on my 95 blazer. I have read a lot of the posts on this particular topic, but my car is doing some things i havent seen yet. First, when I switch from 2hi to 4hi the light goes on, but I do not hear the 4wd engage. If I switch to 4lo the 4wd does engage and works fine..i think. When I switch back to 2hi the light does not go on. occasionally, I will press one of the 3 buttons on the dash and both the 4hi and 4lo blinks. I have recently replaced the actuator under the battery, so i know it is not that. Its beginning to become that time of year when i need 4wd so please help!!!!

Welcome to AF.

Does it help to put transmission in netural ar back up and roll forward a little?
Are your tires a good matched set?
Has it got good vacuum and good clean vacuum lines with any fluid in them?
Is the transfer case fluid and transmission fluid level good?

I did try to put the car in neutral and I moved it forward a bit, but not reverse. I just recently put brand new all 4 matching tires on the car so I dont think that is a problem. I checked the vacum and that seems good. but I have not checked the fluid level in the transfer case or the tranny fluid.