Originally posted by 6BQ5 I added a bit of tin foil in between the batteries and the battery caps. It looks like the battery surface in both doesn't protrude up high enough to contact the caps.
Congratulations. The foil should not have been needed since the 387S is a direct replacement. You might want to carefully pry the contact up a little. It has likely been depressed from use of the wrong thickness battery coupled with wads of foil
There is some discussion regarding voltage and the metering circuit. The camera has a modified Wheatstone bridge that should be resistant to voltage differences, but the circuit is not quite balanced. What that means in practical terms is not clear to me, though I have done meter comparison using the 1.55v battery with several other bodies with good agreement.
Steve