Coax cable can occasionally get damaged so there are some steps you can take to repair the damaged cable rather then changing the whole line. This will save you time and money, because a repair is less expensive then a new coax line. After the line is repaired there should be no difference noticed in signal strength for the TV. If you do notice a signal-strength loss and have followed all the proper steps for repair, then you will need to change the line because the line is damaged beyond repair.
Paint on liquid electrical tape if the insulation covering is damaged but the line is intact. When dry, it will create a new insulation barrier.