you wrote that it does not charge/sync properly - does it connect at all?

the dock connector is soldered to the logic board - so there is no easy way to replace it.

sometimes are the contacts bent or corroded - look inside the connector, maybe you see something "odd"

if they are corroded or dust/dirt is inside - use isopropyl alcohol and a paintbrush to clean it, if they are bent - well, lets talk about that after you checked it