I cant tell, as i havent sorted that out on our 5245 yet, but i think to cure it inside the rear axle housing.
I have new brake parts on shelf, just need to find time to put them in and loosen all the brake joints.
Poor brake performance can also be caused when the linings are soaked in oil due to a leaking axle seal. These seals dry out when the tractor is standing still for long times, and smear oil on the brakes when you use them again.
Another cause is glazing of linigns when they have been used very hard and became too hot, which bakes them hard and then they dont brake very much anymore..