This is the simplest way to reduce the amplitude of swing for those quartz movements with electromagnetic pendulum swingers. Carefully bend the plastic suspension above the permanent magnet away from the drive coil, applying just enough force to permanently slightly distort the suspension hanger to increase the air gap. Try as little distortion as possible and re-bend if needed. Forgive me if is common knowledge or obvious (although I've never seen it mentioned anywhere) and forgive me for talking quartz. I've sometimes struggled with replacement customer quartz/pendulum movements. In some narrower clock cases (e.g., schoolhouse), the pendulum bob annoying swings out enough to contact the case on each swing. I've tried all kinds of workarounds, some reported on this and other clock sites, including adding weight to the bob (does not work), placing tape across the coil and/or magnet (does not work). Adjusting the pendulum length is unacceptable as most of these clocks have a window to view the bob.