Ratching from Front Axle

I'm getting a ratcheting sound from the front axle when I engage the 4wd. Sounds like the axle disconnect area. If that's what it is, is there a fix? I'm going to tear into it tomorrow and see if there is any damage.

Might be a vacuum leak resulting in the disconnect not engaging fully. It's basically a sliding splined collar, not unlike a synchronizer ring in a manual tranny. Shouldn't be any damage.

If you can't find an immediate problem, as a test you can engage it manually and shim it to stay there, and disconnect and plug the vacuum harness. Actually, you could leave it that way permanently.