Gilles found it during his summer tour of garage sales, and left it to me. Many thanks!
The test with batteries is positive, it works perfectly! The 1.7/50mm is like new.
The ME is an automatic aperture priority. Metal curtain shutter, 8s to 1/1000s, flash sync to 1/100s. In addition to the "Lock" and "Auto" positions, the selector offers a flash position (manual, operating without battery) and a "B" position. The ME has no manual position.
Exposure compensation selector with the ISO sensitivity selector under the rewind button. Mechanical selftimer, no depth of field tester, "X" socket. In the viewfinder, display of shutter speeds with diode in front of the selected one.