Remove the CPU cooler and place it with the copper heat plates facing upwards.

Wet the paper towel with high concentration Isopropyl Alcohol, then proceed to wipe away any old thermal paste on the copper heat plate.

Using a new piece of paper towel, wet with Isopropyl alcohol and wipe away any old thermal paste on the CPU die.

Do not touch the exposed CPU die with fingers. Body oil will negatively affect thermal transfer between the CPU and cooler.

If unsure on how to perform this step, please see the guide on how to clean and apply thermal paste.