TC reported that smoke internal alarm atrear M1car. Staff (YCK) checked and confirmed no abnormalit ies. ~~~~~ 1616 TC reported smoke internal alarm. Staff (YCK) checked and confirmed no abnormalities. CE : 1616 smoke internal alarm able to reset. No abnormality.  1616 FC 720 (Smoke Internal). Checked #1E internal smoke detector & found no signs of water/dust ingress. Swapped SDR1 from #1616 to #2616. OPS 20 raised to check on smoke detector.  Celine Tan    45384 BSD: To check no1 end internal smoke detector   #1616 checked and found no 1 end internal smoke detector sensor dusty. Cleaned with compressed air and checked PCB ok, no signs of rust or water ingressed. Function test ok. Done by: Saini, Din, Morgan (2/4/24)