Fire internal alarm. Staff(AMK) checkedand feedback no smoke or heat in rear M1 car. ~~~~~ BSD: To check 1543 no1 end smoke detector  Checked and found 1543 smoke internal detector was dusty. Serviced the sensor. Function tested ok. Done by: Rizman/Jack/Koh/Imran 16.4.24 1543 Fire internal alarm. Staff(AMK) feedback no smoke or heat in at 1543.  1543 FC 720 (Smoke internal). Checked no.1 end smoke detector. No signs of dust and water ingress. Function check smoke detector - ok. No fault reoccurred.  Swapped SDR1 from #1543 to #2544. OPS 20 raised to check #1543 no.1 internal smoke detector.  Sarma/Alan 45393