Watch the Breakdown 3 online guitar lesson by Andy Aledort from Slow Blues Power

At bar 4, the chord progression switches from Bb7 to Bdim7; I like to fret Bb7 like this: thumb (over the top of the fretboard) on Bb (sixth string/sixth fret), index on Ab (fourth string/sixth fret), ring finger on D (third string/seventh fret), and middle finger on F (second string/sixth fret); this way, I can switch to Bdim7 simply by moving the fret-hand thumb up one fret to B, sixth string/seventh fret. The Bdim7 chord form can then be moved anywhere on the fretboard in increments of three frets, i.e., using the same “grip” for the whole chord, the thumb can be positioned at the seventh, 10th, 13th, fourth or first frets, and the resultant sound remains Bdim7 (or its three equivalencies, Ddim7, Fdim7 or Abdim7). Subsequently, the lick played over this chord can be thought of as a diminished seventh lick, as it utilizes the Bdim7 chord tones D, F and Ab.