Had one of these on a limited edition Hello Kitty Tefal Mini (BF8120 is the model I believe). SWMBO decided to dig it out of storage and found that it kept boiling the water without ever tripping the thermostat normally.
Externally about the only thing that felt wrong was there was no tacile (clicky) feeling when the kettle’s boil switch is actuated. Suspecting the thermostat to have internally welded itself together, I took it apart.
The handle section disassembles with 2 screws on the inside under the lid, once those are removed, there is just enough flex in the plastic to remove the lid and the internal steam manifold section to access the thermostat. A single screw holds the thermostat in place, once that is loose, disconnect the 2 wires taking note which wire goes where (this is just so during assembly, the wire’s don’t twist around and cause issues with the plastic going back together, electrically I’m sure it’ll work just fine).
The entire thermostat looks like this.
Filpping it over, the bimetallic disc is visible, using a sharp tool to dislodge it off the catch, the disc slides off.
This is the pin that disengages the contacts internally when the steam is hot enough to bend the bimetallic disc, once the disc is off, the pin can be shaken/gently persuaded out.
Next the 2 catches on the outer edge, near the electrical connections, can be pushed in and the assembly slides apart. I broke the catches during removal but that’s not a big deal, the securing screw will still hold everything in place when the thermostat is screwed back into the kettle.
Here I’ve gently wire brushed and polished up the contacts with a fibreglass pen, mine were welded closed and the this contact had lost the ability to let the actuating lever cam over and hold the contacts closed, some adjustment later on the hump section of this contact fixed that (I had to bend the hump section up slightly as well as pull on the tab that engages the lever, essentially lengthening the hump section, for a more tactile response). Test often during adjustment and go slow, it’s easier to correct a small error/wrong adjustment.
Once satisfied with the feel and after cleaning the contacts up, I pieced it all together and gave the kettle a spin, which confirms it works good again. Hopefully it’ll stay that way for good long time.
