s10 fourwheel drive

I have a 88 s10 that will not engage the fourwheel drive. The vacuum system works and pulls the cable but still won'y engage.

Does the transfer case engage 4 high and 4 low?

I have a 88 s10 that will not engage the fourwheel drive. The vacuum system works and pulls the cable but still won'y engage.

I tried engaging it once again and found that the cable wasn't being pulled far enough. So, I figure I have a vacuum leek somewhere.
Thank's for the reply.