Others, such as those involving plumbing lines, are best left to qualified plumbers. Major plumbing problems are best left to professionals. In order to pinpoint problems that may occur in the toilet tank, it's helpful to understand the flushing cycle. Moving the handle makes the trip lever rise. This lifts the flush ball.
Water flows through the opening in the ball seat from the tank to the bowl.
The flush ball drops back into place, covering the ball seat. This causes the intake valve to open. Water entering the tank pushes the float ball up until it closes off the intake valve. Repairs of 6 Common Toilet Tank Problems Before starting any repair, turn off the water supply valve located under the toilet tank. If there is no shutoff valve under the fixture, turn off the water at the main shutoff valve.