Recently, I asked where the knee locks on the Millrite MVI were, as what came with the mill did not look anything like what the manual mentions ("Where are the knee locks on a Millrite MVI vertical mill?", 4 Feb 07).
Gordon Heaton of the Millrite group on Yahoo has the locks on his MVI, and took some photos for me. His locks look shop-made, and are not as described in the manual either (having a T- handle), but are effective. They have elongated dog points.
Anyway, what I finally did was to find some 2" long 3/8-16 hex socket cap screws with a concave dish in the end of the tip (versus flat or pointed), and use a 1/4" brass ball (from MSC) between screw tip and the back of the gib. With the ball in place, there is enough thread so the screw does not run out of thread before tightening down and clamping the knee. The concave dish allows the ball to wedge between screw tip and gib, despite the 30-degree slope of the back of the gib.
This solved both problems I had with the cap screws that came with the mill: not enough thread to clamp, and screwthreads at tip being munged. It may be that the female thread in the knee stops short of the gib.
The idea for the brass balls actually came from the Millrite itself, as this is how the various calibrated setting rings are clamped to rotate with the steel shaft, without damaging the shaft. In these setting rings, the setscrew thread does not extend all the way to the shaft, and there is just enough metal so the ball won't fall out, and I suspect that the original knee locks worked this way as well. It would also explain why the shopmade kneelock clamps had elongated dog points.