If you have never changed an overflow tube, the task may seem harder than it really is. Follow these steps to get through the process with ease.
Step 1 - Prepare
Turn off the water supply to the toilet by turning the knob on the back of the toilet it in a clockwise direction. Then flush the toilet and use an old rag to soak any excess water inside.
Step 2 - Remove Bolt
There will be a 2-inch bolt at the bottom of the tank for the flush valve. Use a wrench to loosen it, then finish unscrewing it with your fingers. After you have loosened the bolt, you can lift the tank from the bowl.
Step 3 - Replace Parts
Replace any needed parts. You can find a replacement overflow tube, as well as the other parts, at a local hardware store. Just insert the overflow tube back where you removed the old piece. Use gentle pressure to make a snug fit without causing any damage.
Step 4 - Reassemble
Now that you have installed the new overflow tube, you can put everything back together in the opposite way that you took it apart. Make sure that you do not turn the water source back on until everything is hooked up and secure again.
First put the hose back under the toilet, then secure it again with the bolts. Turn the water supply back on by moving the knob in a counter clockwise direction, but do so slowly to avoid explosively high water pressure. The toilet will begin to fill slowly; wait until it has completely finished filling before you do anything else with it. Test the toilet to make sure it works properly.