Besides checking the stability of the chair, you can also consider adjusting the rotation angle of the chair. Sometimes the chair will shake because of the improper rotation angle. Try to adjust the angle of the chair to a more comfortable and balanced position In addition, a cushion can be added to the chair to provide extra support and reduce the possibility of the chair shaking.
If all the above methods fail, the best solution is to seek the help of professionals. If the chair you bought is still under warranty, you can contact the manufacturer or seller for help. They can provide repair or replacement services. If the chair is out of warranty, you can consult a furniture maintenance expert or repairman. They have rich experience and professional knowledge, which can help you solve the problem of chair shaking and let you use the swivel chair with peace of mind.