Check out the video (below) made in response to a customer inquiry. The video demonstrates the very simple cleaning which brings it back to new again--eliminating frustration along with the gunk!
Depending upon the liquid, over time the stainless steel pin and tip can become "gunky". A sticky tip may get frustrating, or it could result in damage to the tip.
Also, watch the video for more tips such as the best way to store your bottles to minimize gunky buildup.
The Best Cleaner Ever™ or other solvent
Heavy-duty Pin, or awl, toothpick, etc
Cotton swab (optional)
PS: Cleaning is not something normally needed to be done often. You may do it every month or every few years, depending upon how long the pin cap is left off, the characteristics of the liquid, if the bottle is upright or on its side, etc.)