Probably. Think about it, ever open something like a 1938 radio that still works? Everything is soldered except that the tubes plug into sockets. Soldering is the most reliable form of wire connection when done properly. The primary reason connectors are in a pinball machine is for assembly....not really for troubleshooting or to facilitate future repairs. You want to solder when you can, and where required use only the proper connectors. The goal is to never have to do a repair in the future by making your repairs more reliable than what has failed, and to try not to add additional failure points. I haven't been in my five games to repair them since the initial overhaul when I aquired them.