A friend of mine brought me an ailing LCD projector; he said that
during a football game it went "pop" and everything went dark. We
powered it up and everything appeared to work normally, but there was
no light output. The bulb appeared to be fine, so I told him we could
probably expect to take it apart and find pieces of transistor all over
the inside.

Sure enough, the power supply has a bipolar power transistor that freed
one of its leads in an effort to escape. I normally do not deal with
power circuits, but I am wondering if we can just replace the
transistor (I would be inclined to replace all 4 of them) and see if
that fixes things. Is this reasonable? Is there anything else I should
replace? Should I do this in a well-ventilated area free of combustible
materials with a fire extinguisher handy?

My second question: The exploded BJT is a Sanken 2sc4297, absolute max
collector current of 12A. I am tempted to replace it with a 10A
Panasonic 2sc3975, which is otherwise mostly identical. Is this a bad
idea? I have no idea how much current actually goes through the bulb.
If anyone can suggest a source for the original Sanken part, I'd
appreciate it. I've gotten Allegro to send me free samples before, but
I don't know how many times I can get away with it.