The yellow wire definitely looks like it has issues. Try delcity.net. Look for Packard 56 connectors. I suggest replacing all of them. And the blue crimped butt splice connectors are not a good idea. These along with soldering and heat shrink tubing are much more reliable:
Use wire of equivalent size or larger. I use a micro butane torch for this but a heavy duty soldering iron will also work. I like the torch because it's fast and instantly shuts off when you release the trigger. Don't use acid core solder. Look for the rosin flux type.