I'm surprised the dot fell off. I scraped the paint out on the 40C I had and tried some glow paint in the hole. I didn't like the glow paint so I bought the brightest white model paint I could find and used a toothpick to drop a bit in the hole. The factory paint was hard to get out. The 3 white dots was too much for me. I had ended up blacking out the two rear dots. I painted them white again when I sold it. Good luck with your new gun.