So my favorite Cobra 29 has a channel indicator that is acting a little funny. It's an older side mic 29 and when you change to/from (or past?) channel 21 a part of the 2 acts like it wants to go out (it flickers a bit). All other channels 1-40 channel display illumination is solid, including channels starting with 2. Do I need to spray some de-oxit inside the channel selector? Or is it more likely the display is going out?