Camera twisting on flash bracket

Hello,
The title pretty much describes my question, I have a Pentax Spotmatic and am expecting an SV arriving soon, and I've purchased a plain, old-school japanese flash bracket with a flat, slotted base that I thought would look contemporary with the cameras, but the camera wants to just spin on the bracket. It's slightly bowed, and I plan to try straightening that out, but I don't think that will solve it completely. How do I get the camera to stay in place on the bracket? I imagine there is a simple, old trick to solve this, I just don't know it.
Thanks

I had a similar problem with a tripod and one of my cameras. From the hardware store I bought a roll of rubbery mesh stuff (drawer liner?). A piece of this stuff between my tripod and my camera snugs the two together sufficiently to eliminate twistage.
Cheap, too.
Ria

YEA,
That's right, I think I know the stuff, the black mesh , people use it to line their shelves, it's made to grip, thanks a lot!