Thought I'd add my rendition -
When the +notes are clustered together it inidcates that they should be blended as one note.
This means don't pause between blows, just drag the harmonica to the next note.
When the + and - notes are clustered, it indicates a very quick in-out-in movement.
+5+6 +6 +7-7+7 +7 -8 +7 -6 +6
A--a ma z-in-g graaaace, how sweet the sound
+5+6 +6 +7-7+7 +7 +8+9 +9
Th-at saved a-a-a wretch li-ke me
+7+8 +9 +8-8+8 +8 -8 +7 -6 +6
I-I once w-a-s lost, but now am found
+5+6 +6 +7-7+7 +7 -7 +7
Wa-as blind b-u-t now I see
