I have an FE that works perfectly and it uses the same battery setup that the FM uses. So, besides my voltmeter, this is my test bed for batteries. So. I went to the battery store and bought a brand new 2L76. That's a single 3v battery that is the other proper one to insert in the camera. And it worked. It tested at 3.26v and initially, it worked. I had LEDs as soon as I turned on the camera, I cocked the shutter and fired it and I still had LEDs but I cocked and fired again and the LEDs went out. I pulled the battery and tested and the battery showed 2.78v. So riddle me this, Batman - in a camera that's Fully Mechanical, in which the only thing that the battery is used for is the light metering system, how is it that battery drain seem co-incident with the shutter being fred?
What is there in an FM than can short and drain the battery?