Is it permissible to use the remaining amount from the price of the motor for other mosque needs (maintenance - works), or must permission be sought from the donor parties first?

It is not a condition to seek permission from the donors when transferring endowed money to another purpose if it becomes impossible to use it for the purpose it was allocated for. This is according to the discretion of the endowment's supervisor. Thus, what is in excess of a mosque's need may be spent on another mosque. And if the endowed item is not utilized for the purpose it was endowed for, it is permissible to utilize it for another purpose.