This got me thinking - since becoming an FI I have had to put up with many small defects including missing or inop nav equipment, balding tyres, dead lights, knackered seats, the list goes on.
Obviously the overriding issue is safety but on the other hand if I refuse to fly because a nav light is not working then I can't afford to pay the rent so that would be silly.
As a flight instructor, not only do you NOT have to put up with these things, you have an obligation to set an example for your student by insisting that these problems are properly deferred, or repaired, or you merely refuse the aircraft. Set and live by the standards of a professional NOW.
You can't afford to pay the rent because you insist on operating professionally? You don't need to refuse to fly the airplane because a nav light is inop...you need to insist it gets fixed.