Just recently I purchased a 1994 220 cabriolet.
When I put the rear head rests down to open the top, or just for visual aid in the mirror, after about five minutes the rear head rests come up like bread in a toaster and there is a terrible "THUD".

Is this normal? Is there a way in which I can lock down the rear head rests?

Appreciate any help from anyone.

Thanks,

Gene