The main problems that are prone to occur when playing vibrato are as follows:

1. The movements are tense and rigid when rolling and kneading, and the coordination of various parts is not coordinated. (Especial attention should be paid to the forearm and wrist not to be too tense)

2. The tiger's mouth moves when vibrating, which affects the stability of vibrating.

3. The relationship between vibrato and pitch is not well grasped, or pitch is affected by vibrato. (Except for "sliding kneading", where the fingers of the left hand slide up and down on the note to be kneaded, other kneading should not change the position of the fingers during kneading, otherwise it will affect the intonation)

4. The method of vibrato is poor and lacks change. (There are many methods for vibrato, such as: sliding, chanting, rolling, pressing, etc. Different vibrato is applied to the corresponding musical mood and style. So it needs to be changed.)