There's a transistor in there but I don't know the location or part number. If thats bad the flipper wont work...

Sounds like a mechanical issue. Check if the spring is still there, which pulls the drop target over a "notch" holding it up. You may also need to take the single drop target assy out and clean it thoroughly - these assemblies were often oiled by operators.

Do you have power at the coil? Is the diode not broken or cracked? Are the wires soldered solid?

Also note that these problems are often related to the flipper switch. Upper flippers often have a double switch behind the flipper button. Try pushing the flipper switch leaves with your finger and see if the flipper works when doing that.

Agreed. Once the drop targets are reset, they have to be hit to drop down again. They dont drop on there own on this game.

We just had the same problem on our Flash Gordon: intermittent upper right flipper, lower right flipper works fine. Problem turned out to be the switch at the end of the lower right flipper EOS stack. It wasn’t making a solid connection when the lower flipper was extended. That switch closes the connection between the upper flipper coil and the flipper switch. We just decreased the gap and the upper flipper works great. Could also possibly be carbon buildup.