C550 shows replace black toner w/new ctg

[integritybob]

I have a C550 that says to replace the black toner ctg and will not allow copying, despite the fact that the cartridge has been replaced, and the "gas guage" indicator shows a full cartridge. I found several threads in searching this forum, but I have already tried most of the solutions, such as checking the contacts/ground plate on the connector to the toner cartridges. I removed the entire hopper assembly and swapped sensors around (no effect on problem), cleaned all contacts, sensors, etc. Thanks in advance for any suggestions.

[samjake]

Re: C550 shows replace black toner w/new ctg

check that the toner slide above the black image unit has opened, this opens when you push in the image unit, the slide jams shut if this happens toner doesnt enter the image unit so the machine thinks it has no toner.

[integritybob]

Re: C550 shows replace black toner w/new ctg

check that the toner slide above the black image unit has opened, this opens when you push in the image unit, the slide jams shut if this happens toner doesnt enter the image unit so the machine thinks it has no toner.

Thanks for the suggestion. I did check the slides, as well as physically verifying that there was toner in the hoppers. In addition, in the sensor check under state confirmation, all the toner sensors are at state "0".

[ivovb]