Lenovo ThinkCentre M55 - Manual (Page 30)

14. Align the beveled corners of the new heat sink and the mounting bracket.
Then position the heat sink 2 on the heat sink mounting bracket. Lower the
lever 1 to secure the heat sink.
15. Reinstall the air baffle.
16. Go to “Completing the installation” on page 34.
22 Hardware Replacement Guide