I am replacing all my oscilators regardless of age or function. I had already replaced one with the Gen2 (and just fixed the settings), so with the 6 they sent me I now have a new one in 5 spots and 2 spares new in the box. plus 5 spare Gen1 models that can act as replacement stationary fans even if they start clicking. Leap day, leap year is easy to remember.
I just have to label the ones I am pulling so I know which were fully functional and which clicked. I found that a little square of foil tape over the oscillating button is easiest for the clickers. You can still use the button if needed.
They may be sending me a box of Gen3 fans before I need to bother with replacements