I am also restoring a Gottlieb High Hand and had the same problem with the drop targets not resetting. I problem on my machine was in the scoring motor reset switches. There is a reset switch for the two upper drop target and a different reset switch for the lower two drop targets. If the switch is too far apart the drop targets do reset but the time to catch and keep them up is not enough. I solved the problem by bending the appropriate reset switch a fraction of an inch closer together. Since I made this change they reset every time. Could you check your machine and look at motor c4 switch. Please tell me what color are the two wires on the solder points for this switch. I have only one wire connected and the other post is not connected to any wire.

You are correct. I have done that and I believe that it must have been tied to a switch below. There is no signs of any missing wire and no wires extending for below. I just wanted to verify that my conclusions were correct, before I connect it too the switch below being Tom has an actual machine.

Hi Tom.
The switch is 4c. The middle one of the three. What are the color of the wires connected to this switch?
Thanks, Larry

From the pictures that you took (thanks) it looks like the top wire is green/white. Is there a wire from this switch that connects to a post on the level under the c level? Thanks again.