I own a 2012 Millennium, third hand. Second owner used the machine very little if much at all. Most of my initial adjustments were carriage bolt adjustments and a small burr on a rail. The 'S' catch disappeared.
I've been troubleshooting a racing stitch regulator for the last several months. I downloaded the Millennium manual from this site. It differs slightly from the manual I received with the machine.
My racing 'stitch regulator' happened when my power cord drifted between the carriage rails resting on the encoder cable. Tonight we corrected the insulated cord clamp loca