We just unboxed a new C368, and on startup it says "Waste Toner Box not installed". I tricked the front door, and when I hold in the Waste Toner Box with my hand, it registers, but when I let go it doesn't. There is a plastic fin on the center back that blocks an optical sensor, it seems about 1 mm too short. There is a large spring near the fin. We removed the spring, and now it registers as installed. The pressure from the spring was holding the fin too far from the sensor. Interestingly enough, the OEM WTB has the spring, and the Aftermarket (Katun) has no spring. Just wanted to post this in case it helps someone.