Basketballs go through plenty of wear-and-tear during games and practices, not to mention just shooting hoops in the driveway. As such, it should come as no surprise when your ball begins to leak. If you enjoy fixing things yourself, can't afford to replace the ball or if the ball has some special value, you may choose to repair rather than replace it. It doesn't matter if ball itself springs a leak or if the valve is leaking -- either way, you can fix it.
Ball Leak -- Option 1
Submerge the basketball in a tub of water and rotate it, watching for exiting air bubbles to indicate the source of your leak.
Dry the area off and mark the leak with pencil or tape.
Heat the tip of an old, dull knife by holding it over an open flame, moving it back and forth.
Swipe the hot knife across the leak on the basketball until the vinyl begins to melt.
Allow the vinyl to cool and solidify for at least 5 minutes.
Push the inflator needle into the ball's valve hole, then re-inflate the ball gently by using a hand pump. Fill the ball to its recommended pressure setting and do not over-inflate.
Insert a wet inflating needle into the valve hole several times to clean dirt from the valve.
Insert a toothpick into the valve hole if the leak persists.
Break off the end of the toothpick, leaving the valve plugged.
Ball Leak -- Option 2
Purchase a ball repair sealant with a syringe.
Fill the syringe with the sealant according to the manufacturer's directions.
Insert the syringe into the ball's valve hole.
Depress the plunger on the syringe, then bounce ball vigorously.