Converter noise

You might want to turn it off, stick something small in to block the fan and turn it back on. If you still hear a squeal with the fan immobilized, it's probably a noisy, failing capacitor in the electronics section. They do that when the electrolyte paste inside dries out over time. While they can be repaired, usually by the time components start going bad it's better just to replace the converter with a new one considering the cost of the part and the labor of getting it changed. Another electronic device that prices have stayed pretty stable over the years and now seem pretty reasonable. If it is the fan, usually the little "computer type" fans have a foil name sticker on one side of the hub. Peel it off and you will find a small rubber disk that closes off the bearing cavity. Pick it out with a needle, put in some 3-IN-One oil (WD-40 dries back out too quickly), replace the rubber, and you should be good to go!