I played with this a bit more and, after many flicking of the switches, they suddenly started working. At first they would occasionally switch but after may cycles, all three work now all the time. This radio was purchased in Dec 1990 and sat unused ever since until I got it from the original purchaser. It is on 6 meters (plug in module so could also be used on 72MHz modules). I got it because I also used to fly on 6 meters (N4MCZ) and decided to try it again. If it continues to work okay I'll put it in a scratch built 1/4 scale Moth I've nearly finished. Even if this is a couple if decades old, I still think it is one of the better units ever made and since it is PCM, should still be quite free from interference from most electrical noise. Edited to remove remarks where I miss remembered a name, mixed up Krysta with AnnMarie. Sorry, old age is ruining my memory.