A long time ago, when I was still sewing on a used machine, all of a sudden my machine clunked to a stop.
I took it in to be repaired, and when I came back, the repair main handed me a (not so small) ziplock bag of the lint that he had extracted from my machine. With a stern look he warned me that I should be cleaning my machine more often. There was so much lint that it had caused some of the metal parts to bend. Needless to say, that was embarrassing, and ever since, I’ve made it my mission to meticulously clean my machine on a regular basis.
Especially these days, when I’m stitching on such a high end model, a BERNINA 750 QE, I try and remember to clean the machine out every time before I sew.
I keep the necessary tools right next to my machine; I use a soft paintbrush, a pair of long skinny tweezers (my Grandpa was a dentist, and these are hand me downs…), and a soft lambswool tool. (I got mine at City Quilter in Manhattan.)
Making sure that your machine is OFF, remove the needle plate, and begin by lifting out any big pieces of lint with the tweezers. Look around for threads too, and remove those.
Then use the lambswool tool, and rub it back and forth over the surface. It acts like a dust magnet. Be sure to knock off all the dust from the lambswool tool when your are finished.
Lastly, remove the bobbin case, take out the bobbin, and use your soft brush to get any lint out from in there. Then use your brush to clean out the area where the bobbin casing goes.
Caution: Do not use pressurized air, which will only force the lint and threads deeper into your machine where you’ll never get them out, which could cause long term damage (see paragraph one).