I've got this 2010 13" MacBook Pro that has a bad RAM slot. I've swapped the chips, used different chips, used one chip in each slot one at a time. But no matter what, it will not see the chip in the lower slow ("lower" with the computer upside down and the bottom removed). If you start with just one chip in the bad slot, you get the single tone of "no RAM found" (as opposed to the triple beep of "bad RAM found").
I took a very close look at all of the pins in both slots, and they all appear fine. I know that the ram slots are part of the logic board, you can't just "swap the slot". But I wanted to see if anyone else had any other tricks you might be able to try?