If the bait won't swim at all, that's a tough one to fix. Are you fishing it with a snap or without? Sometimes a snap will help the action.

You could also try adding some weight to the belly, just behind the hard plastic head. Just push a mojo weight in or a bullet sinker and see if it helps keel the bait. If not, you can take it out but it's worth a try.

A final resort would be to take the bill out and fashion a new one. I'm not totally up on bill making but you should be able to find acrylic or lexan at the hardware store and cut it with garden shears to the shape you want. A larger wider bill could get the bait swimming although you'll probably have to work on it to get it to run straight.

If you do try to tune the bait at all, I would shave the side of the bill before bending the wire nose of the lure. There's a very fine line on those baits between bending the wire nose a little bit and bending it too far and cracking the head of the lure.