It's not just that model. All of the other Hi-Matics with the "ATOM" symbol (E, ES, F, FP, CS) use a special COPAL shutter that combines the aperture blades and the shutter blades together. COPAL did the same for many of the Yashica G35 rangefinder, as well. Minolta called it "ELECTRO-CONROL", but they were auto-exposure only, since the shutter and aperture blades were the same. They also have the "ATOM" symbol.
These shutters are great when they work, but apparently the electronics are "complicated" and reliability is not their strength. Are you sure you are using the correct battery. I thought they all used 640 batteries.