Head Up (Saliva Issues)
Excessive saliva in the harmonica (which causes reeds to stall) is a common problem for harmonica players.
If you practice with your printed study song sitting on a table (if you prefer paper over digital), I suggest you look into getting a music stand. When using the music stand, adjust it at a higher level than you might think. A low stand has your head tilted downwards (just like when practicing with your sheet music on a table), which allows saliva to flow into your harmonica. If you set the stand higher, this will not only give you good posture (for less achy muscles after practice), it will allow you to have your head up, keeping saliva where it belongs, in your mouth, not drooling into your harmonica.
If you use your laptop or computer monitor to view the lesson PDF, place the laptop or monitor on a thick book or two to elevate them.
If you use a phone or iPad, set them on a higher ledge.
Whichever way you practice, the goal is to get your chin/head up. It also helps to tap your harmonica on your leg often, which dislodges spit building up around the reeds.
P.S., the best music stand is the Manhasset Model 48.