I had read that this part can go bad and cause the slow charging. I went on eBay and found a replacement part for $16 (search for "USB Power Charger Charging Port Flex Cable for Asus Google Nexus 7 1st 2012"). I should have tried your suggestion of checking to see if the ribbon cable was loose first, but when I removed the part, I could tell that it was firmly attached. After replacing the port, my Nexus 7 will now recharge. The battery app I have says it is only charging at about 800mA, but before I replaced the part it was charging at about 30mA (yes thirty!) and was taking more than a whole day to recharge. Now it is recharging about 20% an hour which is MUCH better. It took about 10-15 minutes to replace.