Quoted from CaptainNeo:the first picture looks like a toddler soldered that diode. I'd redo that first and make sure you have nice connections. If there are other solder jobs that look like that, you might have splatter in places that is arching on you.
Yeah, practice for 15 minutes on some old parts NOT in the machine.
You got to have solid solder joints in a high vibration location like a pinball machine.