They should float, I bet yours has a pinhole leak that is allowing the bait to fill with water, I had one do that. They can be tuned, they are actually my favorite crankbait (the 5 and 5XD).
Sink it overnight in a cup of water, take it out and wipe it dry, then hang it over a newspaper to see if it leaks and where it is coming from. If it is leaking water, email/call Strike King and see what they can do.