Success! I was finally able to update the maps to 2017.
Make sure you update the firmware to 4.2 first. That's a free download from Garmin.
I found a guy in FL that had the 2017 map update for older Garmin systems (and his prices are very reasonable). It's installed on a 2gb SD card that installs into the KNA-G510. However, when you turn the GPS power on, it still goes to the old maps.
Here's the trick. Connect a USB cable to the KNA-G510 (there's a USB slot right next to the SD card slot). When you turn the 510 power on with a USB cable connected, it will ask if you want to choose Garmin, or memory. Choose the right option, memory. Using a laptop connected to it I removed the old map file from internal memory. I probably could have right clicked and changed the name on the old file and left it, but now I have memory space for other things like different voices and symbols. Now when I turn the power on, it pulls the new map file from the SD card (the SD card must stay in the unit).
Screen shot of new map file on the Kenwood LZ-702W touchscreen connected to the hidden Garmin KNA-G510. .