I’ve just changed one of the exhaust dampers on my R-Sport - the one on the exhaust box. After changing I had a look at it and it was vibrating up and down when the engine was idling. Is that a sign of something more sinister being broken or is it what’s meant to happen?

Based on the design of that damper I suspect it may be normal, but my concern is maybe the engine mounts are knackered too. There are no visible engine vibrations but is there a reliable way to check them?