I’m a beginner myself. Is there a specific hole locking up? Bottom holes, especially some of the draws may leave the impression that it’s broken while the problem is actually you not pulling the air through right. Search the forum, there is info on ‘broken’ 2 draw. There are things you can do to try and improve it. I never tried it myself but the blues band’s I got with the course are candidates for me to thinker with.
-Take it apart and put it back together. Read somewhere that that already could be an option for improvement.
-Search for info on reed alignment/offset. comes down to reeds not being aligned properly in the slots.
-Search for reed gapping. Which comes down to space between the reeds and the reed plate.
Don’t think you’ll get it comparable to a special 20. I bought a Tombo Folkblues before I received JP’s course with the blues band’s. My first impression with the blues band after the Tombo was going back from good to less good. While I do have one of the blues band’s in my car it’s actually the Tombo I take with me in my pocket and play. the breathing through the Tombo in my experience is easier then the blues band. I don’t think that’s something you can easily change.
Good luck, hope you get it sorted!