Vibration, new o-rings didn't help

Hello, we have a 2019 snoo that mostly works but vibrates like an off-balance washing machine when moving. It's most noticeable on the lowest settings, baseline and level 1. Just replaced all the o-rings (and cleaned up inside) and that didn't fix the issue.

A post mentioned that the issue could be the motor spindle or casing. How can we diagnose if it's either of those and is there a diy solution to fix it?

Thank you for any help and pointers!