172 cup brake bias help urgent

[tom_cup]

had my 172 cup a few weeks and today the rear bias valve everytime i let the brakes of makes a clonk

jumped underneath had a look everything is free and moving nicely
with some copper grease on the joints

got the misses to press the brake pedal when she let off it clonked

anyone have any ideas how to make it quiet again cheers tom

 

[sam JFM]

Is it loose on its mounting?

 

[tom_cup]

no mate fixed solid just the arm moves slighty when brakes a pressed then when brakes are released it goes back to the origional position but clonks and it stops

 

[sporty-bloke]

It's knackerd

 

[tom_cup]

great just what i wanted will it be doing its job still but just making the noise car still feels like it brakes fine