The TTL prism viewfinder (with exposure metering) - my knowledge

Since I bought a TTL prism viewfinder with a non-functional metering (of course, it was declared so by the seller), I searched internet for information on how to fix it. But I found only very incomplete information and mostly very misleading (i.e., basically authors' assumptions, but most of the time this was not the case). So, I disassembled it myself and also repaired it. In order to set various (dis)information in right order (= described the real situation), I wrote following shorter summary of my findings. Later on, I bought a printed copy of original German repair manual for viewfinder and modified this text according to it. And still on June 27, 2023, I added a parts of pages related to WK65060 photoresistor (that is, what is in viewfinder, without letter "a" in marking) from catalog Tesla "Electronics Parts 1980 - 1981" from year 1979. This text can be downloaded here:

TTL prism attachment for PENTACON six and PRAKTISIX by L.Ruffer.pdf

And the following is a sample image of its first page:

The Czech translation of the original repair manual is on this website here: Hranolový hledáček TTL - Návod na opravy