Hi Hugh,

I have been cruising the BB trying to find things to read and in doing so I have followed the thread somewhat.
I see that you are hung up on liking the look of the radio and are not onto considering the aftermarket solution.
In being a little humorous, I will suggest taking a picture of the radio with a picture phone or old school camera, and then place the photo over the front using pins so you can flip it up to use the newer radio. I know it’s silly but “When one is desperate one can get creative.” (:)

Now, with all foolishness aside, you can open the radio up and try to fix it!
It’s not working now so you have nothing to lose.
It the best thing to work on and get experience.
With that said,
In my experience with doing lots of like this, (:) I find that if a human hand touches things it can break things.
With these switches stuff like dirt or oils or food from the fingers can make things gummy!
Remote controls fir a TV work with a carbon faced pad touching a circuit board. The membrane is the spring tension that you talk about.
On calculators, there use to be, half domed metal bubbles that touched down. They would grow weak after many heavy fingered thumbs, so they went away!

In the case of your radio the switch could be similar as above or be more mechanical in nature.
The ones used now are small squares housings with a center button pad that the outer button presses onto.
There is most likely a tiny spring locked up inside switch or under the button you touch!
The unit may have gotten “gunk inside” it since the outer push button fits loose in the front face of the radios face plate.
Just cleaning the square button with some denatured alcohol might flush out debris or just cleaning behind the control panel might fix it. The switches are only about .150 of an inch square so the pad is even tinier.
There are two pins or a circuit that can be crossed to bypass the switch so then when you use the ignition switch, it will go on and off. This way, you can wear out the volume buttons! (:)
I think I’m going deaf, so I ignore the volume settings anyway!

A replacement switch can be found out of a myriad of electronic devices thrown away everyday and everywhere! Get two or more, if you find some, for the next radio!

So, it comes down to are you willing to tear open “something broke?”
Think of it as a challenging adventure of using your hands and mind, to ease it back together too!
If the ordered radio is the same, you have a blueprint to work with or it will take lots of pictures! (:)

Keep us posted with your progress!
Some of us are desperately bored!

Phil