However, a small factual correction to the pot at KEV is necessary: the manufacturer was "PGH Leuchtenbau Staßfurt". The design of this fixture was “optimized” around 1978. The “optimization” consisted solely of the fact that they wanted to save aluminum. The original design (Andy has such a pot) was manufactured by “VEB Leuchtenbau Leipzig”. The housing was made of thicker cast aluminum and the “reflector” was made of sheet aluminum. The “optimized” design had a housing made of thinner cast aluminium and the “reflector” was now made of black bakelite, not even painted white on the inside.

For those who are curious, I dismantled an unused ‘pot’ of this type. The problem was the ‘pairing’ of the materials steel (the screws) and cast aluminium (the housing).
After many years of repairs, these connections were very difficult to loosen, and the screws occasionally broke off in the process. Here you can see the individual components:

That’s kept extremely well inside there , or have you cleaned it up, that ballast is mint!