[Bring_Back_Shantz]

Okay, I didn't read every word of your post, but a few things stuck out at me.

I'll start this with saying this. There is no such thing as an untrainable dog, especially labs. They are just about the most food/fun oriented breed, and can learn to do just about anything with enough patience, repetition, consistency, and kibble.

Firstly of all, you said he's obsesed with tennis balls, and you've tried to get this out of him. WHY? You've found a VERY STRONG motivator for your dog. If he'll do anything to get that ball, then instead of trying to train it out of him, use it as a training tool to work on the other behavior.

Secondly, the biggest problem with any poorly trained dog is almost always a lack of consistency/repetition from the owner. With a new baby in the picture I'm not suprised things have gotten worse with your dog. You say you don't take the dog places and and he gets excited and it makes the problem worse. Chicken and egg man. The dog is bored because you don't take him places, then when you do he gets excited and freaks out so you decide not to take him places. You're short on time, and the dog is missing out on the attention he used to get, it shouldn't be supprising that he's acting out, especially since it's a lab, which are usually pretty quick to figure out what they can get away with, when the owner isn't around/paying attention.