hi iak65
So it looks like they're ZA- they don't slide down by themselves
I still have them, but after unsuccessful attempt to sell them few times on fleebay I decided (rather got funds) to carry on with my cnc mill project as planned.
That's the screen capture how I plan the mill to looks like
Click image for larger version. 

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Basically structure is going to be 6mm steel plate milled to size + I plan to fill it up with epoxy granite for extra rigidity.