Bingo, I believe this is exactly how the Wiselite plates were done. I remember being quite horrified when I first saw them, years ago. It displays a great lack of creativity and ingenuity in terms of how to fixture a plate and/or keep it from warping. I seem to recall these did have some warping issues too, some being a bit bowed.Didn't the latest batch of plates that Wiselite made have the holes in them in those locations? Supposedly there for their "fixture"? I can't remember if they welded up the holes afterwords or not but I think that is a Wiselite plate.
Ah, hadn't noticed that. It appears that the area where the top cover fits is not milled, so that notch is the start of that profile, from the end of the top plate. From there to the feeday, it has to be milled down to spec.So what is the little notch in the top of the plate for?