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The grates: The grates of the stove need to be Kashered through Libun Chamur. [If one cannot do Libun Chamor to the grates, then one is to clean them very well and wrap the grates in thick aluminum foil that will not tear throughout Pesach. Practically, it is customary to cover all grates with tinfoil even if it was Kashered through Libun Chamur, as explained below]
Burners: The burners are to be Kashered through Libun Kal. One is to first lean the burners well. It is advised to use toothpicks or needles to remove any dirt or food from within the gas holes of the burner. Afterwards, one is to turn on the fire for some time to accomplish Libun Kal.
Stove top surface: The stove top requires Iruiy Keli Rishon. One is to clean the stove surface well and then do Iruiy Keli Rishon to it. If the surface is made of non-Kasherable material, such as enamel, that it must be covered with aluminum. Furthermore, it is customary to cover all stovetops with tinfoil even if it is made of a Kasherable material, as explained below.
Knobs: One is to clean the knobs of the stove very well, cover them or attach clean replacement knobs.
Covering all items: Practically, the custom is that even after Kashering all the above parts of the stove, one covers all the surfaces with aluminum. [See Halacha 5 in Q&A]
 Piskeiy Teshuvos 551:19
 Admur 451:24; Rav Wozner in Kuntrus Mibeis Levi 1:29
Other opinions: Some Poskim rule it only requires Libun Kal. [M”B 451:34; Igros Moshe 1:124; Piskeiy Teshuvos ibid]
 The reason: As at times [Chametz such as] dough spills onto them and they absorb Chametz directly without liquid. [Admur] Now, although we rule that two pots which touch each other do not transfer taste without liquid [Admur 451:67] perhaps we suspect that liquid may spill onto while cooking and make everything prohibited according to our custom to prohibit the food even if the pot is not be Ben Yomo.
 See Admur 451:65; 67; Rama Y.D. 92:8; Taz Y.D. 92:29; M”B 451:34; Halacha 5 above!
 In any event the pots never touch the burners and there is thus no suspicion that Chametz absorbed without liquid will transfer into the food in the pot. Nevertheless, Libun Kal is to be performed in order to destroy any Chametz Beiyn from inside, and Kasher it from majority usage.