I have that machine! Mine is the Tula Pink Edition. I don't think that the feed dogs have excessive noise. This is my 3rd Bernina, and by far my favorite of all my machines. Have you talked to someone where you bought your machine? Have you gone to the classes offered by your dealership yet? They are a wealth of information, and you could talk with the teacher about it. I discovered an amazing site that has 170 videos on the Bernina 770, you would learn a lot about your machine.
sewingmastery.com/bernina/
Good luck with your new machine, the 770 is an amazing machine!
One last though, have you cleaned and liked your machine properly? In my opion, my machine always sounds a little rough when it needs a cleaning and oil.
