A waving monitor probably just needs a cap kit, or could POSSIBLY be a failing flyback.
Remember, if it is a Galaga "on location" then it has probably spent 20+ years on location.
perhaps with a minor vacation in the 1986-1989 era when Galaga wasn't "cool".
in the 1986-1989 era when Galaga wasn't "cool".Lies! Filthy lies! Galaga is, was, and shall be the Alpha and Omega of my video game addiction, and has been since I was a child. So shall it be everyone else's. Give in to the Galaga, all of you.
The screen was "waving", like a constant sine wave throughout the entire monitor.