I have a 96 s10 Blazer and the 4 wheel drive won't engage but when you push the buttons you can hear it try to engage and disengage.

And if you put it into 4x4 low it won't engage the front axle, it will just keep me in low gear for awhile til I can get myself out of it by repeatedly pushing the buttons.

So I was looking through different threads and found one case may be the accuator under the battery. I looked at mine and the rubber around it was kinda torn up. How do you tell if they have gone bad or not?

And if that isn't the problem what else might it be?
(sorry if its a repost, I couldn't find anything about the front accuator working or not...)

 

You can test the actuator with a hand vacuum pump with a gauge on it. Pump down the actuator and it should pull on the cable. You should be able to pull a vacuum on it and have it pull the cable in. The vacuum should hold steady. If it drops, then the actuator has a leak.

You can then put the vacuum gauge on the line from the transfer case. You should see intake manifold vacuum at this line in 4HI and 4LO and nothing in 2HI. If you do not see manifold vacuum or close to manifold vacuum (get a reference vacuum level by connecting the gauge to an intake vacuum port), then there is something wrong with either the vacuum line to/from the transfer case or a problem with the vacuum switch on the transfer case itself.

The engine needs to be running for any of these vacuum measurements on the lines. The actuator itself can be tested with the engine off.

 

Excellent, very similar problem. Buttons will no longer work in park or drive for 2hi and 4hi. Playing with the buttons got me stuck in 4lo.
At one point I could shift between 2hi and 4lo but now nothing will move. This was working until the lovely wife put it in 4lo to go through 6 inches of snow plow stuff at the end of the driveway.