Get a pack of fuzzy crafting pipe cleaner type items, from Hobby Lobby.

Take a few of them, fold them in half, so there is no poking wire end. That might poke an upper pad.

Twist them together. Dip in rubbing alcohol, Squeeze out most of the alcohol.

Insert into the mouthpiece end and brush it out a bit.

Q Tips work also,

This will remove any mold mildew and buildup.

Strips of cotton cloth run through the horn will also work.

Alcohol is the holy grail of mold mildew breakdown.

Good Luck