How did you clean the switch stem? They look brand new after your cleaning. I have lots of old dirty switches that need to be cleaned.
I use PB1 and water.
And rinse many times..
After rinsing.. I clean them in the ultrasonic cleaner.
And I rinse again.
My wife said "Water is more expensive than switches"
And one of korean kbder find new detergent.
It is very effective for removing dust.
No bubbles..
I sometimes use it when there is much dust in the switches.