You drop your instrument on its head and the head breaks. Happens quite often with erhu, pipa, zhongruan, liuqin, cello and double basses.
You drop your instrument on the floor and a crack appears on the body. Happens to erhu, pipa, zhongruan, liuqin, guzheng, yangqin, cello and double basses.
Missing | Dropped Parts
Once in a while, parts on your instrument goes missing or gets detached. Some examples are frets, bridges, fushou (unmovable bridge on pipa) etc.
Strings deaden over time and as a result affects the tone of the instrument. Whilst it is easy to change them on the erhu and zhongruan, the same cannot be said for Yangqin or even Guzheng.
Fret buzz occurs when the vibrating part of one or more strings physically strikes the frets that are higher than the fretted note (or open note). A small buzz is annoying but a severe buzz can reduce sustain and dampen the tone. Can occur on all fretted instrument like Pipa, Liuqin, Zhongruan etc.
Most players should be able to tune their own instruments. Some instruments require specialized skill sets to tune them. Some of these instruments include the Sheng, Yangqin, Dizi, Gong etc.
Frets will wear out over frequent usage. There will come a point of time where you have to remove all the frets on the instrument and install a new set. Most often on Pipa, Liuqin and Zhongruan.