Replacing the flapper on a TOTO toilet, regardless of the red or blue color, is easy.
Turn off the water supply: Locate the shut-off valve behind the toilet and turn it clockwise until it stops.
Flush the toilet: This will drain most of the water from the tank, making it easier to work on the flapper.
Remove the old flapper: Unhook the chain from the flush lever by gently pinching the clip holding it and releasing the hook. The flapper might be hooked onto two little pegs inside the tank. Simply lift it out carefully.
Install the new flapper: You might need to adjust it based on your toilet model. Refer to the instructions on the back of the package for chain length, lever hole position, and any flapper adjustments specific to your toilet.
Turn on the water supply: Slowly turn the valve counter-clockwise until it opens fully.
Check for leaks: Observe the tank as it fills. Ensure there are no leaks around the flapper or at the connection points. You might need to tighten the flapper arm with the adjustable wrench if there’s a leak around the flapper itself.
Test the flush: Press the flush lever and observe if the toilet flushes properly.