Charging Jack Won't Charge!

A common problem with v710's (and actually all v series dumb phones) is that when you plug them into the charger the phone either won't charge or they charge intermittently, depending on how good the connection is to the charger plug. I have one v710 that won't charge at all and another one that only charges if I put a great deal of pressure on the connection by hand. As soon as I let go, it stops charging. Does anyone know what the problem is and is there a known fix for it other than just getting another phone?