It would be a waste to throw away a good stainless steel kettle just because the whisle is not working. Actually replacement parts for the whistle are sold by some vendors but finding a matching one is a real headache.
One of the reed (tiny metal plate that vibrate creating sound, often made from brass) of my whistling kettle broke when my wife tried to clean the reed chamber. Steam would rush through this large cavity and there would not be any whistling sound when the water boils. Actually I did not know that the reed was broken before opening up the whistle assembly. After repairing it, my kettle works fine again, like when it was new!
Step One - Open the screws that hold the reed chamber and top handle of the cover. Remove reed plates from the reed chamber. This whistling kettle has two reed plates and each plate has two reeds. It is made from brass but sometime you can find stainless steel, plastics or aluminium ones. This reed works just like the reed in your good old harmonica. When air rushes through the tiny gap, the vibration would create a whistling sound.
Step Two - For my case one of the reed was broken, so all the steam would take the easy way out through this large gap. Therefore, there was no whistling sound whenever the water boils. I used a metal sticker (the ones that are used to patch pots) to cover up this cavity. Then I pushed the other reed back in place to reduce the gap to enhance the whistling sound intensity.
Step Three - Fix the reed plates back into the plastic chamber which is actually the top holder. Screw back the plastic top holder on the kettle cover. Fill the whistling kettle with water and test it out.
The video below shows my repaired whistling kettle in action! he he he, just like a new whistling kettle! LOL!