I am hoping someone can help me with this: We have 6 of these projectors at school, they were installed about 4 years ago. One of them now needs a new bulb but I cannot see a model number anywhere on the projector! I have googled the make of it and it looks as though there are at least 3 different versions it could be so I don't want to order any bulbs before I know which model it is. They are all in security cages so it is difficult to see on the top, does anyone know anything about these projectors? Where might I find the model number??