If you're using Schmetz needles in your machine, each needle has a color band near the top end of the needle - the color identifies the size (and type) of needle. Go to
www.SCHMETZneedles.com for a print out sheet of all the various colors & their size & type. It's a one page print out. For instance, the common Universal 80/12 has a red band of color. If only one band of color, it signifies the needle as Universal(no color). Others, like a Topstitch needle, will have a band color of Teal ( for any size of Topstitch needle) & another color band that identifies the size of the needle. The print out chart makes this easy.
Haven't tried this, but try inserting a piece of paper clip, a small wire, or maybe even a toothpick in the slot where you plucked a new needle from. Move it each time you select a new needle.