Take a look at this tuner..

http://www.niji.or.jp/home/k-nisi/5t50.html

I bought one of these (and the associated Lux LRS amplification) over 30
years ago. Some months back I pulled it out and set it up in my bedroom to
drive a pair of Mission speakers.

This equipment had been sitting unused for almost 20 years, and it had (and
still has) quirks that need fixing. Most of them are related to dirty
switches and controls.

One of the worst problems was the Tuning buttons on the 5T50. As with many
dirty or aging switches, a single press caused multiple closures. Tuning was
extremely clumsy, as the frequency would jump multiple channels with a
single press.

"Look! Up in the sky!"

So I pulled the lid off to clean the switches. Uh-oh. They were sealed and
there was no obvious, simple way to remove or open them. What to do? Working
on the principle of "try anything", I pulled off the buttons. This isn't
difficult -- they snap into place -- but there's this huge, weak spring that
provides the restoring force. You don't want to lose it.

I guessed that the button's shaft directly poked the switch contacts. So I
squirted some cleaner into the switches.

Bingo. The switches now work correctly.

Sometimes things work out just fine.

--
"We already know the answers -- we just haven't asked the right
questions." -- Edwin Land