To fix a Parker pen spring, first, carefully open the pen by unscrewing the barrel. Locate the spring inside, usually near the refill. If the spring is bent or stretched, try gently reshaping it to its original form using your fingers or small pliers. If it’s damaged beyond repair or missing, replace it with a new one of the same size. You can find compatible springs and pen accessories at office supply stores or online platforms such as Parker Pen PK. Once the spring is fixed or replaced, reassemble the pen by putting the refill and spring back in place and screwing the barrel tightly. Test the pen to ensure it writes smoothly. Handle the parts carefully to avoid any further damage.