I was hoping you would get an answer to your question. i have owned a few wings 84 - 86 and have had this problem with all of them. sometimes the switch to change channels sticks, i sprayed mine with WD40. also, when i hit a bump one of my earphones would cut out or i would get a high squeal through them. I think it is the way they are wired myself.
the radio buttons on my 1500 were sticking so i sprayed them with electrical contact cleaner and that corrected my problem. i was going to use wd40 but thought that what i used was better if the contacts were dirty