The body of the dulcimer is a frame of wooden structure, and when it is subjected to a tensile force of about 2,000 kilograms for a long time, it will generate internal stress, which makes the body easily distorted or deformed. When the body is twisted or deformed, the top is torn.

When the shrinkage seam of the piano panel reserved for the dulcimer is deformed and closed by force, the stress from the piano surface can no longer be relieved. Under the continuous action of the internal stress caused by the tension, the panel will appear bulging.

When the direction of this force is bidirectionally dislocated to generate force, the piano panel will be torn and cracks and bulges appear, and this phenomenon is more obvious when the temperature or humidity suddenly changes. The way to deal with the bulge is to cut the shrinkage seam and form the function of the shrinkage seam of the piano panel again, so that the panel can automatically shrink and maintain the state of use. If there is cracking, use the following methods.

When the dulcimer soundboard is cracked, different repair methods can be adopted to compact and stick the panel according to the degree.

When there is a small crack on the dulcimer panel: use a sharp blade to open the crack in the direction of the crack, apply white glue evenly to the paulownia wood strip with a suitable width, insert the paulownia wood strip into the crack, and tap it lightly with a hammer , requires tight bonding, and finally flatten the surface of the molding with a shovel, and smooth it with a 180-mesh emery cloth along the direction of the wood grain.

If there is a big crack on the piano panel: loosen the strings before repairing, flatten the dislocated panel with a clamp, cut the crack into a V shape with a sharp blade, and select the appropriate paulownia wood with the same color according to the size of the crack Strips, and evenly coated with white glue, tap it gently with a small hammer, require tight bonding, use a spatula to level the excess part, and use 180-grit sandpaper to smooth it in the direction of the wood grain .