As well as all in this world, the lenses Carl Zeiss are not eternal. They serve very long, but not always the it can be careful, and sometimes comes the term for service.
For those who wants to repair the German or the Japanese lens Carl Zeiss or the camera of the same company (Zeiss Ikon, Contax, etc.) I can recommend the site Zeiss Ikon Contax Camera Repair.
carl zeisscarl zeiss85Surprisingly, the owner of a workshop answers very quickly and offers even the difficult repair including restoration of an enlightenment (removal and drawing new) and gluing together of elements (sticking and pasting back with new optical glue).
I give an example.
This lens Carl Zeiss Planar 85/1.4 was in perfect condition, but it was used (these lenses were made in 2005, this copy is quite fresh)
After about a year of use it began to gain defect which you see in pictures.

As it became clear, the central gluing together ( from masters words) becomes unstuck. It is possible to repair, but it is necessary to sort, stick elements (3 pieces), to clean it, stick together back and to collect.
According to my data (the optical scheme) there is only a back gluing together from 2 elements and hardly there is a problem. But he is a master, and he decides. I didn’t see the better service yet.

New lenses

The new lenses Carl Zeiss ZE, ZF, ZF.2 also can have both factory, and acquired defects. Extremely seldom, but it happens. One of cases (I saw a lot of them) it when some electronics falls off. In this plan of the mechanic it is more reliable.
Here is a message:

On how I understood, in this version of lenses the electronic drive for management of a diaphragm from the camera is installed. How long this block will work? Since I got used Planar 50\1.4 ZF.2 which I used very often, with no working CCP. Opening showed that a flexible payment being pasted on not drying glue (as on an adhesive tape) was displaced aside and contacts didn’t get on the platforms. So that – any electronics is not on eyelids. Than were famous manual Zeiss…