M.B. realised that this was a troublesome item when the cars were in production. They tweaked the electronic specifications to try and get them dependable and reliable.
There advise is to get the latest model of OVP available. As the previous poster has mentioned - why risk expensive components for a comparatively cheap item.

Rubber products and electronics decay over the years whether used or not. In the electronics industry we know there is gradual deterioration of electronic components due to slight alteration of chemical properties of materials, static and electrical or RF interference. These problems manifest themselves ranging from intermittent faults and operation to ultimate breakdown.