During train prep found 2539 intermittent stuck brake. To rectify. ~~~~~ #2539-fc 308/312/330/331. Swap ACU 2540/2539 fault transfer. Replaced ACU and function test ok BCP within criteria. ACU no abnormalities. #2539-ACU-New s/n: 1301-125  Old s/n: 1019-019. Not: 2308104 Raise. Done by Saini/Asruddin.25/08/21