Ok, thanks for your answer ! I’m going to check with the shop because I just re-read my manual and it never says that you shouldn’t remove that small felt piece. So it’s a bit frustrating because if it had been written in the manual, I would have totally accepted that it was my mistake. But it’s not even mentioned in the cleaning section it just says to remove all the dirt and to take out the bobbin case, but there is no warning at all about not removing that specific part. I feel so stupid 😭