I just picked up a new to me Nikon FM, which looks pristene. Put in two A76 cells and slapped a AF 85 1.8 d lens on it. Indecates the FStop in the viewfinder and LED lights on the '-' in the right side of viewfinder....all good to go... The light meter never changes, even when pointed directly into the light. I have gone through my wide collection of lens and even tried some with stopped-down modes. No go. Is it busted, or do I have to do something I don't know about?