Pull "Chicken Cluck"
If when performing the pull (taught in Tongue Block Study 3) you hear a secondary sound, immediately after performing the pull, then you're adding an extra, unneeded articulation.
You're either using the "K" articulation immediately after the pull or closing and quickly opening the glottis (sometimes referred to as a "glottal stop") immediately after the pull. Both actions are not needed and creates a slightly strange "chicken cluck" sound.
If you think the chicken is attacking your pulls, performing the pull very slowly and you should only feel the tongue release from the face of the harmonica (where the tongue releases its seal from the face of the harmonica/lips) and nothing else. If the back of the tongue or your throat is doing something after the release, this secondary action is what you want to get rid of.
Happy New Year To Everyone!