steve is right. it involves many factors. another thing would be if the trem posts are not level with each other, you'll get less flutter. even the position of the tremolo. if it's leaning back too far, you may get less flutter.
even if the
tremolo arm bushing is loose, it could affect the amount of flutter. check everything, especially the posts and knife edges. make sure nothing is rubbing anywhere.
i've seen this a few times. one of the saddle screws is sticking out too far and touching the wood underneath. "many factors" to quote steve again.
and you'll need to check all of them. :-)
john