Our tv set was preinstalled as well, although on a newer model. The set doesn't swing out or swivel but if you will feel up from the bottom, there might be a release that you can trip to take the set off the bracket. At least that's they way ours was attached. The bracket releases at the bottom and them has a little round rod toward the top that comes out of the "hooks" toward the top and then the set is free, free, I tell you.
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