What I find is that with the exposed heat pipe coolers when the "pea-sized blob in the center of the CPU face" is used the ridges and valleys on the heat sink bottom often interfere with the spreading of the paste across the surface. What I recommend is:
First, clean the old paste off both the CPU and the heat sink. Paper coffee filters are ideal for this because they are a smooth, shiny (and insexpensive) material that doesn't leave behind insulating fibers like paper towels, kleenex or soft cloth. Start with a dry coffee filter to remove the bulk of it and finish with one moistened with isopropyl alcohol.
Then turn the cooler "bottoms up" and lay down two parallel lines of thermal paste perpendicular to the copper heat pipes from side to side across the bottom of the heatsink. Make the paste lines as think as possible while still being continuous. Space them evenly so that the bottom of the heat sink is divided into three approximately equal sections. This way, the ridges won't prevent the spread of the paste.
