When it comes to overhauling harmonica instruments, especially older models, special tools and equipment are not commercially available.
 For example, newly manufactured bellows structures and bellows fitted with new bellows strips are very rigid in their elastic properties. The bellows trainer presented in the book is a good tool for restoring the required elasticity to the bellows.
 After machining on the appropriate tool, distorted instrument housings receive the necessary sealing to the bellows frame.
 After processing, the soundpost soles seal again to form a filling, which prevents wind loss and improves the tone response.
 Other tools such as sorting boards make work much easier. Some of these tools are commercially available but are easy to make yourself.
 82 pages, text on construction and function, 45 color illustrations, 36 drawings, DIN A4 format, ring stapling, 1st edition 2020, ISBN 978-3-00-065974-4