Superior Threads in America have a Dr of Threadology – Dr.Bob; if you go to their website
it is full of wonderful information
and here is a true and salutory story from their June 2013 newsletter:
Lint is defined as an accumulation of fluffy fibers. We have lint in clothes dryers, clothing, and unfortunately, our sewing machines. The lint which we find in our sewing machines is mostly from threads, fabric, and batting. Cotton produces more lint than spun polyester. Lint is a result of friction (or rubbing) against the thread. Think of how many contact points the top thread touches during the threading process. There are thread guides, tension discs, levers, and the needle. Each contact point causes friction which results in lint coming off the thread. A little lint is to be expected. However, excess lint can be bad for your machine because it can cause your stitches to be misaligned, feed dog operation malfunctions, fabric puckering, and thread breakage. Regular cleaning and maintenance is recommended for all sewing, serger, and longarm machines. Many machines come with a lint brush to remove lint from the bobbin case area, thread guides, and the needle area. Please refer to your machine manual for proper care procedures.
From the outside, your machine may not show signs of excess lint buildup, but that doesn’t mean that your machine is is clean on the inside. The images below are photos we recently took. A friend wondered why her machine was not working. The machine looked fine from the outside (see the far right image). The needle plate and surrounding areas do not show signs of lint build up from the outside. Only when the cover was removed, did we find the problem, and what a problem it was!
These are actual photos
What is the key to reduce or eliminate lint? Don’t use low quality or cheap fuzzy threads. By stitching with high quality cotton threads, you will notice that there will be less lint buildup inside and outside your machine.
for more information!