IME its usually pretty easy to change, and a lot are the same, but not always, your techys should be able to whip the top off, take a look and then decide if its going to be straight forward or not so, and if its a standard or proprietry unit. If they cant do that I'd be suprised and also lacking in confidence..
That said, a service manual can often help - thats what they are for! sometimes a simple job can take hours when you "work it out as you go along" whilst if you had the manual it would take much less time.