The exhaust break damper pivots and linkage are prone to rust build up an ware over time.
So I apply some high temp lubrication to all the areas that need to be free moving.
I have had good luck with Super Lub. A product like it is also available from Cummings.
The turbo waste gate actuator assembly is pron to the same problem, this is an item to have checked at your engine service center when you have work done. The linkage in many cases almost impossible to access, unless one is very nimble !