The anvil is located below the stapling head. It serves to bend, or crimp, the staple around the back of the paper. It is rare that this part needs replacement, so be certain to check for proper alignment between the head and anvil. Poor alignment can mean a poor crimp, or none at all on one leg of the staple or the other.
Other things to check include the staples you are using. Bargain priced staples purchased at many office supply stores are made from softer steel alloys. These staples tend to jam the heads on RAPID staplers, and also have trouble penetrating multiple sheets of paper and crimping properly. If you feel all of the above are okay, consider the stapler head. Because your stapler head receives the most wear and tear of any part on the machine you should expect to replace it at regular intervals to maintain bind quality and prevent unexpected down time.
