I seem to be having problems with a base unit for the T7406e.I have 2 handsets and can't seem to get them to register to the base unit. Customer is getting mad because of the difficulties of diagnosing the problem. I’ve tried everything I can think of to get this to work. At this point I am assuming the base unit has flaked out .Any tricks in trying to get this to work or should we just order another base unit and be done with it.Thx.