20qt Hobart question

I am not very experienced when it comes to mixers, but we have a hobart a200 that we purchased recently and it seems to work fine, but i've noticed a noise that comes from it that almost sounds like a little friction.  It's not coming from the front (where i believe the gears are), but from the back (where the motor is).  It almost sounds like as the motor turns, it rubs some of the metal on the back of the mixer, specifically at the round piece that is screwed into the back of the mixer.  I have no idea what are normal noises when it comes to something like this but i did want to see if there was anything i could do to ensure that all is well. I may be able to supply additional information or even video/sound recording if that would help, though i'm not sure what kind of quality i could get. Thanks for anything,

Chris