Russian balalaikas like this one on the foto - Moscow style 80s - never were  signed by hand. All titles were printed or had rubber stams - rere exaples.
So if you see the balalaika with sheet of paper inside signd by hand - know that is a fake.
Such craftsmen as Serzhantov, Rodin,  Emelianoff or Tokarev - contemporary craftsmen - cant sing their masterpiece by hand. This is so indeed. Shame on ebayer who swindle buyers.