Hi Kevin, and a warm welcome to the forum. We all like to learn new things and tinker here.
For my two bob's worth, I think John; (FAST GRASS), is right on the money....Victa often came up with ideas that for some reason or other that were never to see the light of day....for example, the fabled edger groove that was cast into the bases of the Models 4, 5 (Special) and Sheerline.
However, they could also left over from the casting procedure itself as well....as John says, one of our members may shine further light on it.
Once again Kevin,
