Anyone know who actually has a new replacement battery in stock? I've looked a few sites and either they're out of stock, or they say to contact Minelab. The Minelab site doesn't even list them as being available. Do I have to go through their service center? Are there any aftermarket makers for them? RNB makes a piggy back one, but, I want to replace the internal battery and keep it (somewhat) waterproof.