The solo begins with a repeated arpeggio idea. The pickup and first bar is an Em7 arpeggio over the G7 chord that the rhythm section plays. This produces a G6 (G-B-D-E) sound which is a real signature sound of western swing. The second bar uses the same shape but drops the B down a half step to Bb. This changes makes the arpeggio outline a C9 sound (C-E-G-Bb-D). Changing one or two notes in arpeggios like this is a smooth way to be able to navigate quick changes. Try using other simple arpeggios ideas over different chord progressions!
Repetition is a very common technique in western swing guitar and the second lick is another great example of this. This one again highlights one note to exaggerate the differences between C7 and G7. Over the C chord the lick bounces around the Bb (b7 of C) where over the G chord the lick uses the B (3 of G). Targeting like half step differences between chords like this is very useful especially in blues playing.
The third lick uses some swing and early bebop vocabulary. The idea begins with a small sweep up a G arpeggio and back down the scale. The second half uses a pattern to target the notes of G (G-B-D). The pattern is a scale tone above and a half step below before playing the chord tone. It does this for the D, G, and B notes and finishes with the pattern over a D up and octave. Approaching chord tones like this is another easy way to play through moving changes easily. Try improvising using chord tones by approaching them with different combinations of half steps, whole steps, and scale tone from above and below!
The fourth idea is focused around a chromatic run over the C7 chord. The chromatic run starts on the high E string on the D note and walks down chromatically to the Bb. In addition to arpeggio based ideas, simple chromatic lines like this are very common in western swing guitar.
The western swing solo ends with a quick straight eighth note line. It runs through six different arpeggios in four bars. The first idea is a tritone substitution using arpeggios and some chromatic passing notes to outline A-Ab-G. The ending takes from a common jazz turnaround (can be seen at the end of the standard “Lady Bird”) and uses a simple 1-2-3-5 pattern to get through the quick changes (Bb-Eb-Ab).