The machining of the part of the chair that slots into the wheel base hole is has too much gap space in it and the chair is constantly wobbling. There is nothing really to do to fix it - it's just machined poorly with too much gap space. Low quality parts = chair that wobbles
this is a complete waste of money avoid at all costs
Edit: The customer service said the "free play" of the chair is a feature - this is the biggest waste of money I have spent on Amazon in 10 years