Re-install the mounting assembly and mounting ring (taking care to securely tighten the mounting bolts on the mounting assembly), then re-attach the garbage disposal, drain pipe, and dishwasher hose in the reverse order you detached them. Wrap the rope of putty around the top of the flange like a collar, then insert the flange into the sink drain opening until snug. Now grab a palmful of plumber’s putty (available at hardware stores, home centers, and online) and roll it into an eighth-inch to quarter-inch-wide “rope” with a length roughly equal to the circumference of the flange.
Use a plastic putty knife to scrape off the old plumber’s putty around the top of the flange, then wipe off any putty residue with a damp rag. Lift the sink flange from the top of the sink. Loosen the bolts in the mounting assembly with a wrench, then pull down the mounting assembly and set it near the disposal. Loosen the screws in the mounting ring that connects the disposal to the metal mounting assembly beneath the sink, then pull down the disposal and carefully set it on a clean, dry surface. Start by loosening the screws securing the main drain pipe to the disposal, then loosen the screws in the metal clamp securing the dishwasher hose to the disposal and detach the drain pipe and dishwasher hose from the disposal. To reseal the leaky flange, you must first detach the garbage disposal. Leaks near the top of the unit are more likely to show themselves while the sink is plugged, while side and bottom leaks are more noticeable while the sink is unplugged. If a leak isn’t immediately apparent, remove the sink stopper and pour a few more cups of dyed water down the sink drain, then check for leaks again. Inspect each of these locations while gliding a light-colored rag over the unit the dyed water will readily show on the rag and reveal the location of the leak.
In any handy container, mix a few drops of food coloring into a few cups of water, and pour the dyed water onto the sink stopper to help you locate the leak. Then insert a watertight sink stopper into your sink drain and wipe the unit dry with a clean cloth. Prior to testing the garbage disposal for leaks, unplug it at the wall outlet and turn off the power from the breaker box to prevent electrical shock.