I have a bunch of aging instruments I need to tune up. One common
problem with these things is the buttons become flaky over time.
(I'm not sure what the name for this kind of button is, but what
I'm talking about is a "stateless" push button, which functions
like a computer keyboard key. It is typically used to increment
a number or move a cursor or something. You push it and it moves
the cursor one space. You push it again to get another space.
Often, if you hold it down, a repeat kicks in after a delay of
a half second or so.)

Over time, the contacts inside the button become dirty or oxidized
or whatever and the button becomes flaky. You have to push hard
to get a response, or you get multiple responses from one push,
etc.

If I can get the button open, I can usually improve it by cleaning
it with alcohol, but sometimes even that doesn't completely fix
the problem.

Does anyone here have tips for this kind of thing?

I'd especially like to know if there are tricks for fixing these
without opening the buttons up. There are a lot of different
kinds of buttons and some are hard to open and some take me
a while to figure out how to open.