If you don't find anything decent after a search of the Sound Ideas sound effects library, you should know that you can substitute one sound for another.... and in some cases, it can be a pretty wild substitution.
Case in point: several years ago, NPR produced a radio version of Star Wars. The guy in charge of the production was Ben Burtt, the guy who did sound effects for the first Star Wars movie, Episode 4.
Remember the scene when they're briefing the rebels before they attack the Death Star? They changed the computer's views on the battle station a few times in the movie.
But how do you do the same thing in the radio show? Ben Burtt chose to use the sound of a Kodak Carousel slide projector changing slides. Pretty slick.
So the point is this: the are all kinds of impacts you can select from if you can't find the precise one you need... or you can go record some yourself! You got a camera with a microphone on it, don't you?
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA