As the others have said, using cotton (thread, fabric, flannelette, batting) ..... and you are going to have lint. Nature of the beast ... and really there is nothing wrong with that!
I have the 820 .... and use Aurifil almost extensively, as it is a lower-lint thread than many others!
The joy of your 820 .... it is EASY to clean out the lint.
I was thankful for that, as I have had modern machines that cleaning, was far from an easy task.
For the 820, I do it at least every time I change the bobbin and sometimes in between.
Even if the bobbin is not emptied, clean it anyway ... and stay ahead of the lint.
Take off the needle plate, and clean in that area.
Plus with your brush, reach in behind the bobbin from the top down and from the bobbin door in.
I will say ... I don't like the brush that came with my machine, and have a few others that I like better for doing that cleaning.
Remember ... DO NOT blow air INTO the machine to clean.
Only brush ..... or if you have a mini vacuum tool.