Testing your heat sink for an air bypass is a part of regular maintenance. See steps below to ensure your heat sink is sealed properly:

* Remove the heat sink

* Place heat sink in the palm of your hand, blocking the holes on the bottom.

* Please make sure the holes are covered, or the test is inaccurate.

* Extend the stem, and try to draw air (sucking in).

* You should not be able to draw ANY air through the stem.