Hi darwinsbulldog,
you have to look in the complete English rules link mentioned in the first paragraph of the rules.

Clearing Jams
All players whose guns are jammed (see Jamming Guns below) may attempt to unjam them during the jam clearing step. In order to attempt to unjam his guns, a pilot must have performed a non-restricted maneuver with a direction code of S during the movement step. If this condition has been met, the player rolls a die; his guns are successfully unjammed (and are back to normal) on a roll of 4, 5, or 6.

Hope this helps,
Nick.