I assume you are referring to pcb-mounted momentary contact switches. The
best remedy I have found is WD-40. Use the nozzle tube and apply a small
amount right to the small gap where the actuator protrudes from the
housing. Then rapidly & repeatedly push the actuator about 20-30 times.
You may have to apply the '40 more than once. And of course, clean the
PCB afterwards. I assume it's the foaming action of the WD-40 that allows
it to get to the contacts in the switch. At any rate, it usually does the
trick.

Dont do this! Without wishing to start yet another WD40 war, the
damaging effects of WD40 on electronics are well documented. The
manufacturers of WD40 themselves do not advise applying their product to
electronic components.

There are plenty of products designed for the purpose of switch cleaning.

Ron(UK)

Wow, I'm surprised to hear this. And I'm not being facetious. I can only
assume that this "war" raged on before I started reading this newsgroup.
As I mentioned in an earlier post, I'm new here, just getting my feet wet.
And my only intention is to pass along what I thought to be good advice.
I would like to hear more about the WD-40 debate (or skirmish), perhaps
you could drop a short new post? I would like to hear more. But I would also
like to clarify my point. I serviced consumer electronics for 27 years
before
I retired due to disabilities (3 years ago), and I can't ever recall having
to
re-service any unit due to the use of WD-40. As I said, use only a small
amount of the product, applied right where it is needed. And cleaning up
afterwards. We're talking about miniature switches, handling only keyscan
pulses from a processor. And I certainly wouldn't expect or recommend
using it where higher power circuits are involved. It's just that I can't
visualize a small amount of WD-40 on the surface of a pcb causing a
problem.