Canned Air - CAUTION!!!
Please, please, please don't used canned air to clean your sewing machine or serger!! I just got back from my heirloom sewing class, and while there, the sewing machine repair person showed us what happens to a machine that has been cleaned in that way. It looked like someone had stuffed cotton balls into the bottom back of that machine after he took the outer case off the machine. He said the canned air just drives the fluff from the thread and fabric back into the machine. Don't blow into your machine, either, as the moisture from your breath can cause your machine's innards to rust.