Help! Canon 100-400 has loose internal components

I have a Canon 100-400 II that takes wonderful shots, IS works, etc, but when handled it makes a clunking sound when shaken (or, not really shaken but turned around). I thought at first it might be the IS unit, but now that I look into the lens I can see the internal components vibrating severely. Something is loose! Anyone have this problem before? Any simple fix?

Thanks

Make sure that the lens was actually shut down properly. Put it back on the camera and turn the camera on/off. See if this fixes the issue.

Try mounting the lens, then turn off IS, then turn off the camera, then dismount the lens. Perhaps the IS system needs to be parked?

I can dig out my lens to see if it does the same thing but others might have some input too.

Edit: goaler beat me to it

I am an idiot. I never let the IS unit shut down properly before unmounting it. I have been using IS lenses for fifteen years and never noticed this. I probably had this happen before but fixed it the next time I mounted the lens on the camera. Thank you guys...your solution worked perfectly. I love these forums!

I had the same problem with this lens. It seems to be more susceptible than others I have used.