I am looking for some device that can emulate someone tapping with a wrench every 20 minutes. More specifically, I have noticed that in my application, my flowmeters (rotameters) are dropping over time. As a workaround I have been able to tap them with a wrench every 20 to 30 minutes, this causes the rotameters to rise back up to their original flow rate reading. The fluid in this case is chilled city water. The device I am looking for must be small and not take too much space. Thanks!