Rear-view mirrors 'bouncing'

We have a 2004 L322 Vogue a when we try and fold the Rear-view mirrors in (we have a narrow driveway) they fold back and then ‘bounce’ open again. Any ideas what the problem is and how it may be corrected?

The ‘angle down on reverse’ on the nearside mirror works ok btw.

Any advice would be appreciated.

Rod

Anybody? Out driveway is rather narrow and it's only a matter of time until the nearside wing mirror gets scraped.
R

Oops - I meant wing mirrors not rear view.
Rod