Wrong note tape job (a creative training solution)
Student Mike Cox and I were working on playing 3rd Position in Minor yesterday... specifically holes 4-10. As the study on the site states, you need to stay away from 7 draw. It can be challenging for a student to know where they are on the harmonica, especially when playing quickly while improvising, so here's a quick fix that I suggested for Mike.
Take your bottom cover plate off and using a piece of tape cut to size place the tape over the 7 draw reed (if you use painters tape it will minimize residue when taking the tape off). This way when you go to accidentally play that 7 draw you get nothing! After some practice you can take the tape training wheels off.
Mike thought I should share this with you.