Sometimes with use, a nib may lift off from the feed. This can happen if pressure is applied to the nib in excess of what it can tolerate. If you slide a piece of paper between the nib and feed and it slides in easily, there is too large a gap. This gap can prevent capillary action of the ink to the paper, and you may find your pen runs dry. Vintage pen feeds were usually hard rubber, and can be reset using hot water. This is not for those without experience though, so if you find your pen is running dry, and there is a gap between your nib and feed, consider having your pen looked at if you’re not comfortable resetting the nib and feed yourself.