Every 2nd time I change bobbins, whether replacing and empty one or changing color, I thoroughly clean my machines. I have a littl vacum that attaches to the big vacum cleaner. I use it but not every time. I do have service and check ups on my machines, at least every two years. They tell me that my machines are some of the cleanest they see, and I don't have a lot of extra expense to keep them running great. I use soft long hair paint brushes to get down into my machine, plus the brushes that came with them.