Hello, Rodion. When the venting button is depressed and you blow through the melodica, how much resistance is there? It varies a lot between different brands and models. The more freely air vents through, the easier it is to expel moisture. I have a Hohner Instructor 32, which I believe is the same as the Student 32, and it’s a little worse than average in its venting. I once experimented on a Suzuki Study 32 (similar level melodica) that didn’t vent well, and the experiment was a success. It eliminated the problem.
I haven’t taken the Hohner Student 32 apart, so I don’t know if the same procedure can be done on it. If you can’t get no satisfaction with this Hohner, though, I’d suggest trying a Yamaha P-32D or a Suzuki M-32C. They cost a bit more, each about $70 U.S., but they’re well worth it.