Hi, folks. This is Eric Matusewitch, Boris' son. While my father did not do major concertina repairs, he was quite handy at more minor repairs, such as fixing loose mole skins on the reeds. He had to be handy, because years earlier--when he toured the US with dance partner Rod Strong--he found himself in small towns with no bellows repair shops. Although I never learned to do minor repairs, I often watched my father repair his and his students' instruments. Hope you find this helpful.