Already two 7D's landed on my table, who had obviously defective card readers. On closer inspection, it turned out that the pins were bent by inserting the cards with too much force and thus triggered a short circuit, which prevented a smooth function and led to the error 'No access to memory card'.
So I sat down and tried to fix it. And in both cases, the procedure was a complete success. Pins just bent and available in full length, the cameras work well again.
Blarksel / Kai