Did you try to take the pole off and see if it was the source of imperfection as @Vow3II suggested? I purposely bought the Rackbrutes because I knew from seeing a couple that the quality of the build was very good. I didn't want to mess around with powering something or having a 'flying bus cable' to mess with. I think my only gripe about the Rackbrutes is that they didn't really incorporate 'airflow' through it and have seen a couple modifications that use the 'laws of physics' for some natural airflow.

I would verify if the pole is the cause...if it is, its an easy fix to get a different one. Also as @Vow3II suggested, contact Arturia...they actually have decent support and respond pretty quickly to help requests.

JB