There are many reasons why a stapler might jam. The most common cause is thin staples with blunt points. When pressed hard, these bend and get stuck. To avoid this, only use the type and size of staples recommended for the device. Also, make sure to punch staples directly through paper rather than at an angle. A staple may also jam when stapling more sheets than the recommended capacity of the tool. To keep an electric stapler from getting jammed, make sure to replace its spent batteries regularly with fresh ones.