They are exactly the same tuner pans as the later model Stringmasters.
As someone who has spent a lot of time looking for parts for these, I can tell you that they don't come up very often and, when they do, they are really expensive! If you find a set for a reasonable price and you only need the top 4, I'll have the other 4 off you!
There's a thread here about how WD are going to re-issue them so you may be in luck!
http://bb.steelguitarforum.com/viewtopi ... ec10e411a6
While you're waiting for either of the above to happen, you could apply a temporary fix by just fitting 4 individual vintage Kluson (or Kluson clone) tuners. They are just held in place by the pan and don't need to be mounted on a strip. You just have to drill a hole in the shaft for the string to thread through.
For the bass side, you can just use regular tuners but for the treble side (as per your picture) you'll need a left handed set (or take the tuners apart and put them back left handed which I know Basil Henriques has done and even posted a video somewhere).
