Is it permissible to work in repairing the machines of a McDonald's restaurant, knowing that it serves unlawful meat (haram) and alcohol, and supports the Zionist entity? And does dire necessity make this work permissible? If it is permissible, is the use of the salary restricted to the amount of need, or is it permissible to use it in full?

If you know that the restaurant uses its machines for both permissible (halal (definition)) and impermissible (haram (definition)) purposes, then it is not lawful for you to work on repairing them, unless you are in need of the wages to the extent of your necessity. However, if you do not know, the basic principle is that the work is permissible and the wages are lawful.