I have been doing mine when I wind a new bobbin. When I start a project I fill several bobbins. When they are going and I have to wind some more, I pull and clean my bobbin area including using a vacuum with a small attachment I have for sewing machines. I worked in a quilt shop that repaired machines and that is the advise he gave me. I never use can air, I have seen what that will do with an enclosed bottom to the machine with a drop in bobbin. My older machine that is not drop in, I will use can air, since the whole bottom is open. I do not oil my newer machines since the user manual does not tell where to oil, I let the service man do that once a year. My older machines I do follow the manual on oiling also. Keeping your machines purring is important.