Provided the sockets and wiring do not show any obvious degredation (rust, corrosion, salt creep, burning, melting, yada), then likely your ballast has flown south. I did a little research and found some reports that suggest that these ballasts have a habit of going out.
You can either order a new ballast (google nanotuners) which will cost about $80 for a kit you need to assemble, or you can probably get a new one from the manufacturer.
Inside the ballast pack is likely two individual ballast units, one for each lamp - though I'm not sure as I don't have any direct experience with this unit. If you are willing to take on the project and aren't afraid of working with electricity, you may be able to save some cash by replacing just the ballast inside, rather than the whole deal.