Matt Bigwood

I recently got a set of used manfrotto 520MVB legs (not 525 as it says in the thread... sorry), but there seems to be a slight amount of creep and the leg starts to slip even though the clamp feels tight.

I'm reluctant to over tighten the tightening clamp in case I strip the thread. is there a way of making it firmer? It seems there's a metal bar on the back of the assembly which is pulled onto the leg as it gets tightened, but as it's metal-on-metal it looks like it could slip.

Can anyone offer advice?

Thanks

Matt