the clip tabs do wear down, to where you feel it "click" but it only holds if there is nothing weighting it down..
i also had a cheap cable that came with one of those DVD/Surround Combo Sets, and it wouldnt stay into anything but the DVD player (like they purposely built their stuff that way.)
try putting some paper/tape around the jack to make the connection snugger. (dont cover the optics though),
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