Right in the area you mention (right side between "-" button and right side convenience key) is rock solid on my 8320. I would have to hit it with a hammer to move it (though please don't ask me to verify.
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Mine is made in Mexico as well...
T-Mobile GSM phones: T-Mobile G1, Blackberry 8320 & 8100, Jasper S20, Razr, SE T610
Sprint phones: PCS Touchpoint 2200, Samsung 3500