I clean my machine after every bobbin change and oil it , My machine has a much larger bobbin and a thread cutter, brand new 830.My older 930 from many years ago has never been cleaned in a shop, runs perfect still, I have done many years of sewing on it, but I make sure it is clean after every bobbin change, this helps me to remember when I cleaned it last , also put 1 drop if oil on the bobbin area, not on the bobbin itself, I have not always had a shop to take it to so I do it myself,Q tips and small brush works wonders I use and old electric razor brush works great According to my new dealer , I will take it in for a cleaning every year, so next year I will go to Flagstaff for an overnight stay and get it cleaned