Question: If a kettle stops working because of an electrical fault, and it is repaired by a non-Jew, does it require tevila?
Discussion:
The Shulchan Aruch (Yoreh De’ah Siman 120 Se’if 10) discusses a situation where a non-Jew creates a utensil with materials that are owned by a Jew, and rules that the utensil does not require tevila.
The reason given for this (by Tosfos, Avoda Zara 75b, quoted by the Beis Yosef) is because the utensil is referred to as belonging to the [Jewish] owner, not the [non-Jewish] craftsman. The Bedek Habayis says that even according to the opinion that maintains that a craftsman acquires a utensil by improving it, here in this situation (where a Jewish owned utensil was repaired by a non-Jew) there is no obligation of tevilas keilim, because “the utensil is referred to as belonging to the [Jewish] owner” therefore it is dissimilar to the utensils of Midyan [which is the source in the Torah of tevilas keilim].
The Remo (ibid) quotes an opinion (the Ritzbo) who obligates the utensil in tevilas keilim if the repair [of the non-Jew] is significant and the Remo writes that the utensil should be immersed without a brocho.
Answer:
In your situation where a kettle is repaired by a non-Jew, the most ideal would be to immerse the kettle (as per the view of the Remo), but without a brocho.