Charging jack sloppy, won't charge

The USB charge port on the Kindle may have been loosened over time from use. The charge port is soldered to the logic board and often times the solder joints will loosen and break free. If this is the case then you can usually just solder the loose pins back in place. You may need to replace the USB charge port if the original port has damage such as broken pins and so on. You can use the guides here to get the back case off. Inspect the charge port for loose solder joints or other damage to determine if you need a new port or can resolder the current port. Hope this helps.