Putting a few twists in the rubber bands on each side so it's about as secure as the rubber shock mounting of early HDD installations in the likes of the Compaq Portable II would be better than foam if the heads are overcoming gyroscopic amplification of the HDD's considerable mass. But I doubt it's shaking much as is, unless there's something wrong with it.

A little vibration is one thing, a Mexican Jumping Drive would be another. )