I'm almost too embarrassed to show this, but...
...I finally took some time this past weekend to clean out my travel machine, the Janome Jem Platinum 720. I mostly use it when I go somewhere away from home to sew, so it usually spends most of its time in the travel case. I never seem to get around to giving it a good cleaning.
The photo shows what happens when you wait too long to clean. My machine had been a bit noisy lately (but was sewing just fine), so I opened it up for some surgery. I removed a lot of lint buildup (and I mean a lot), added a few drops of oil, and closed it back up. Now the machine is a lot quieter. Oh, yes, I changed the needle, too.
See that big hunk of lint in the left center of the picture? That was in the bobbin case! I'm amazed the machine sewed at all.
I resolve to do better and not wait so long to clean my machine!