So I have a LW3, PinBot, Black Knight, and Escape from the lost world (6809) that I have added additional LED playfield lighting to. Much of the lighting requires 12v DC power. The additional lighting on these machines plugs into the service outlet (via wall warts) inside the cab. I made a simple alteration to the wiring so the service outlet no longer bypasses the ON/OFF switch on the bottom of the cab, otherwise the added lights would never turn off. Yes, I’m already aware of the fact that this type of modification is frowned upon in the pinball community. That aside, I wanted to know what the proper method of splicing is in a situation like this. What gauge is this wire and what splicing method is acceptable and safe (solder with heatshrink tubing, crimping, wing nuts)? I have wing nuts on now but I’m concerned that in the future they may loosen and cause heat/arcing. Am I over thinking this or would it be acceptable to confirm the wing nuts are tight and simply inject hot glue into the wing nuts to stop any rotation or loosening?

Thanks for the advice. I did not have to add any additional wire, all splices are on the wire that was originally part of the machine. If I were to add another in-line fuse to the outlet what rating fuse would you suggest?