Well there is always stamp collecting. All you need is a tongue, stamp, and paper.
But you decided to go all out and raise pinball hell. And here we are now.
I do hope you know some basics, how to solder, how to use a meter, toilet seat up or down if you are married. If not consider Google or YouTube - lots of good info there and practice can help you immensely when you are in your game.
Jumping right in I know what is wrong with your game. But we need to check one thing first. Hopefully you have a manual for your game, or download one from the Internet Pinball Database. In there you will find instructions on how to use the diagnostic buttons on your coin door.
And on your coin door frame are two switches that open and close with the coin door. To check any high power items like coils or flashers you need to enable the high power switch so high power works in test. Hold in with your fat finger is good enough.
Find coil test, stop on right gate, and check it - does it open in test ? Most likely it will.
Moving on your game's error alert system know absolutely nothing about coils ( gates ) it does know if a ball went by and hit the next switch in the lane where the ball goes. You need to figure which switch that would be, left or right past the gate.
Now I could waste time and tell you all about switch edge test and check that switch and it will work in test. But it is failing in game play. Your machine already told us that. You need to replace that switch with a new one. The old one is gunked up inside with flux or something.
When you replace the switch get the wires in the same spots and the silver band end of the diode facing the same direction.
It should be pretty simple and a good way to get your feet wet so to speak on learning more about your game.
LTG : )