Check out what Clay has to say: http://www.pinrepair.com/em/index3.htm#drops

I don't have a schematic for that game, but if you can identify the switch that powers the coils that reset both banks of drops, check to see that the contacts on that switch are clean and that the contacts are not too far apart. They have to make contact long enough to give you enough current to fire the coils strongly.

If that switch is OK, it's possible that the coils have moved over the years or the metal arms that the drops ride on have worn on the bottom side, reducing the height they reach when pushed up. There are some screws holding those 2 reset coils in place - those screws go through oblong holes that allow you to move the coil one direction or another. Pull the plunger of the coil down hard with your finger and see if the bar that goes across the 4 drops under the metal arms is lifting all of them high enough to catch.

I'd check that switch first, though...that's probably more likely.

Both target banks go through motor 2c. Clean and gap that switch.
Capture (resized).PNG

Capture (resized).PNG

Glad you got it sorted.