One may fix makhshirei okhel nefesh on Ḥol Ha-mo’ed. Makhshirei okhel nefesh are appliances or utensils needed to prepare food. These include stovetops, ovens, mixers, knives, and skewers. Even if fixing them will require a professional and be time-consuming, even a Jewish repairman may be hired and paid for his work. Just as it is permitted to do any melakha necessary to prepare food for the festival, so too it is permitted to do any melakha necessary to repair items which are used to prepare food. Even if one could ask neighbors to cook on their stovetop, it is still permissible to call a repairman (SA 540:7; MB ad loc. 28).
There is one difference between preparing food and repairing an item. Food, even if it could have been prepared before the festival, may be prepared on Ḥol Ha-mo’ed. This is true even if the preparation requires expertise. In contrast, if an item could have been fixed before the festival, but the repair was pushed off to Ḥol Ha-mo’ed, it may not be repaired on Ḥol Ha-mo’ed. If one did not intentionally push off the repair until Ḥol Ha-mo’ed, but was lazy and did not manage to take care of it before Yom Tov, it may be repaired on Ḥol Ha-mo’ed even by a professional (Rema 540:8; MB ad loc. 27; SHT ad loc. 23).
All this applies to makhshirim. Makhshirei makhshirim (items used only indirectly for food preparation) may not be repaired by a professional on Ḥol Ha-mo’ed, even if it was impossible to repair them before the festival. However, they may be fixed if it can be done by a layman at no cost. For example, a fishnet may not be repaired professionally, because the net is not integral to food preparation in the way that a stovetop or oven is. It merely helps in catching the fish (SA 541:1). Similarly, if food is stored in the attic, and the ladder needed to get the food down is broken, it may not be repaired professionally. This is because the ladder does not help directly with food preparation; it helps only in gaining access to the food. However, the ladder may be fixed if the repair can be done by a layman. Similarly, a dining-room table may not be fixed professionally, nor may a dishwasher or countertop, since these are all makhshirei makhshirim.
If the kitchen faucet breaks and it would be difficult to use a different sink for food preparation, it may be fixed even professionally. It is deemed a makhshir okhel nefesh, as it is responsible for supplying the water for drinking and cooking. Similarly, if there is a blackout, a professional may restore the electricity, as it is necessary to illuminate the dining room and to allow the electric oven and urn to function.