switches could be dirty, it happens on my 85 too. Squirt some wd40 in to clean them out or you can take them off and soak them. once they are working spray in contact cleaner. Thats what I do when mine get sticky, seems to work for my radio and cb. Hopefully thats the problem.
It was the handlebar switches I was talking about cleaning.
I cannot tune mine from any other place but the handlebar switch.
I can use the presets on the radio but they have to be tuned using the handlbar switch. If it is like mine, 85 aspy, if you have had the radio off the bike for any length of time then the memory power will have been lost and the presets I think are lost so it might seem it isnt tuning.
My radio (Clarion AM/FM) wouldn't tune either, and my trouble turned out to be worn-out switches. I was able to get all new switches from digi-key and solder them into the old membrane circuit board. Not an easy job, but now I can tune and save presets.
The FM (but not AM) cuts in and out on occasionfor some reason, but is an unrelated problem.
I have the same problem with my 98 goldwing SE. Troubleshoot my wiring from the radio plug and found to be tuner switch. Don't trust the aftermarket books, the wiring diagrahms are wrong. Just use a meter and it is not that hard to find out. Also, mine has passanger tuning adjustment to use, does yours.