QUOTE(Andrew_Roy @ Sep 18 2006, 04:25 AM)

That's probably because the ship's health must be modified to trigger to the rumble.
That is correct. There is no way to rumble if you are also using cheat codes that affect that same address.
So if you want to rumble when the ship is hit in Star Fox you can't have an invincible code on. This is because the health at that address never decreases (because the code is allways keeping it constant).
The rumbles work based on "change" in value. So if a code makes it so a value never changes (like the number of lives, haelth, bombs, etc...), then the rumble will never be triggered, because it doesn't detect any change.