To correct a worn tip, trim away worn material with scissors or a hobby knife.
The tip of the pen does not need to be depressed with a lot of pressure, the paint dispenses easily. When needed, depress the tip on a piece of scrap cardboard to increase the flow of paint. Also, take care to avoid snagging the pen tip on ties, spikes, and edges of the rails. This will help increase the life of the tip.
Click here to see what to do when the tip is wearing out on Track Painters.