I love the mascara brushes that you can get at the Dollar store. They are wonderful for getting the lint out of all those tiny crevasses. A few years back, I got a digital copy of the service manual for my Janome 4900. Since then, we take the top and bottom off the machine and give it a thorough cleaning and oiling, about every 6 months. I am always amazed at the amount of lint that collects in the body, just to the left of the bobbin area.
But now, we are going on holidays and the machine is going in for a full service. I am hoping that will cure some of the tension and feed dogs issues that have cropped up.