cleaning momentary push button switches

[Keith]

Hi,

I've got an old piece of test equipment that has momentary push button 
switches which are the primary "input" or control.  While most of them 
seem to work, many of them are sticky, mushy, and just don't have a 
positive click.

I'm not totally adverse to simply replacing them --- assuming I could 
find an exact match.

Is there a way to effectively bring these back to life?  Can I lube 
them?  What should I use? How should I apply it?

Thanks

Keith