Vacuum Cleaners Discussions

I recently did some internal work in our Miele canister vacuum and I forgot to replace the internal think felt pad which was laying on top of the motor.  I don't think it has any structural purpose, and may be some sort of  (unchangeable?) filter. But if fit so irregularly and gave the impression that it really didn't do much. The machine sounds fine. Maybe it is to muffle the sound? One video did refer to it as a 'filter'. It was full of dust, but that may be because of dust getting through the motor over time. I'd rather not open up the machine again if I don't have to. Any advice on it's function, or its need to really be there? Thanks.