If the back light in the CB-1 display is no longer bright enough for you to see the icons clearly, then it is time to replace the back light foil, officially called the EL Unit Assembly. This is a soldered in part and requires that you disassemble the CB-1 case. There are a few small parts that will fall out of the CB-1 as you remove the back of the unit so keep some masking tape handy to keep the parts in the right position by taping them in position until you are ready to assemble it again. 

NOTE: The temperature of the soldering iron must be +/- 260 degrees Celsius. Too hot an iron will damage the circuit board. It's fairly straight forward to replace the foil. Just note the orientation of the original foil so you get the new one in with the correct side facing you. The all white side is the front of the foil.