What kinda grease? Lithium grease (I got handy)?
I opened the case, did an inspection. The push-button with mehanical contact is soldered to a small board with speaker selection buttons and earphone jack. I couldn't even get the board fully loose.
The switch sez M7 TV-4 4A/64A250V.
I dunno ...
Thx, P
"Mit der Dummheit kaempfen Goetter selbst vergebens!" -Friedrich Schiller