Laptop charging issues?

I've replaced the normal Compaq Presario CQ62 charger before because the third prong on the charger itself came out in my wall outlet. When I got the replacement charger, I've only kept it in a padded laptop case in its own pouch to prevent the same thing. I've had the laptop for two years. Just this past week I've had issues with the laptop charging when the lid is open; sometimes it works but mostly no. As far as I can tell, nothing is wrong with the charger except for the same prong having fallen out despite my efforts.