Then you mite want to clean the sensor that monitor the waster toner box pull out the waste toner box and look for the area that show clear plastic then look for those area of the machine and blow the old toner from those areas waste toner mite have gotten on the sensor saw they can not see the clear plastic and think that the waste toner cart is still full. Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/normanj_7893313f0751935f