It's my first post here

After a first trial (Belem Tower, located in Lisbon - Portugal), I noticed that the printer bed shakes a lot. I decided to unplug the bed and I noticed that there is a conveyor belt (obvious) that I can adjust, attached to a Bosch aluminium profile suported by 4 bearings. And the aluminium profile shakes between the bearings (these bearing are covered by rubber).
Any one noticed this??
Thanks!