I found some OEM Mercedes chain guides for my w111. They were manufactured in 1971 and the problem is the plastic/rubber material on the chain interface. It looks like the material has softened and almost melted in areas from sitting for so long. Maybe they are coated with a wax like material for packaging from the factory and this has contributed to some issue that will be resolved once they are clean? Maybe the tolerances back then were such that some melt was expected? Or the plastic has simply deteriorated past its expiration date?

Any experience with this or knowledge of what they arrived like decades ago?

Thanks.

Don't even think about using those old rails.
Howard