Jumpy bumpy cd changer!

Ok, so a standard 6 disc changer under the passenger seat in a late 2000 ES. All good as long as the car doesn't move but as soon as it does then the slightest tiny bump in the road makes the changer jump. A common problem with cd players in cars but this one seems a bit too sensitive and is jumping at every opportunity!

I've had a butchers underneath and it all seems solid and secure with no wobble so I'm not sure what to do now.

Any ideas? Thanks