Use the following tips to fix a running toilet in your home.
Adjust the lift chain.
Check the inlet valve for trapped dirt and examine the seal on the inlet valve assembly for splits or cracks. Water level in the tank should be one-half to three-quarters of an inch below the overflow pipe. If the level is too high, adjust the fill valve.
Check whether the flapper or tank ball is worn or making a faulty seat. To see if the stopper ball is worn, flush the toilet and rub the bottom of the stopper with your hand. If the color rubs off or the rubber crumbles, replace the stopper ball.
If you need to jiggle the handle to stop the water running after a flush, you should oil, tighten, or replace the flush handle. It is causing the stopper to stay open and water to continually flow in the bowl.
Make sure the refill tube from the inlet valve is not pushed too far down overflow pipe, causing draining action.