Noticed the sticky flipper buttons too on brand new out of the box Avengers IQ and Godzilla. Did not see this described on Pinside yet, so here are some more details and pictures.
*** Warning, OCD ahead ***
When you press the flipper button in, you can sometimes feel it binding or "scraping" against the button housing. Sometimes the flipper will stay in the up position for a second, then the button "pops" out. My first reaction was to switch the machine off and check the flipper mech. But the button housing is the problem here.
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You can easily tell if this is the issue by pressing the flipper button in and rotating it with your fingers. If you feel any "scraping", there's your problem.
This is not even a new thing. My Ghostbusters and Star Trek had the same issue, with a slight variation. And this time, it was after a couple of months of play and a lot of slap saves, I guess. The stamped "3" was what caused the binding.
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The solution is to simply take the button apart and file off the binding part (inside edge of the button housing or the stamped "3"). Don't take too much off, or the button will not stay in the housing anymore. Had to replace mine on ST.
