That's probably what has happened. The two halves are wore so they are clamping but just not enough. You think that just making a shim from a can tin, cutting it the same shape as the halves should do the trick?
I was thinking to file the bevelled faces so that they where smooth again and then the inside of each halve to make them smaller so that when I thighten them it will clamp tighter. But the shim is a much better idea just need to make it fit as @mdcc_tester mentioned.
That's probably what has happened. The two halves are wore so they are clamping but just not enough. You think that just making a shim from a can tin, cutting it the same shape as the halves should do the trick?