John Deere 920 bizarre noise

I bought this discbine 2 Falls ago and it's worked better than anything I could have ever had with a sickle mower but it does make almost metallic noise by the gears on the left side of the unit. I know there are a couple of large gears on that side but I'm not so sure if this noise is good or bad. Been doing it since I bought it so I don't know if it's supposed to be loud. Sorry if it's too vague.

John Deere 920 bizarre noise