Laserjet won't print - Remove cartridge lock on display screen

[Jlock1981]

Printer will not print. On the display screen it states Remove Cartridge Lock.

The locks have been removed (the plastics ones) already. The cartridge has been in the printer and has been printing for quite some time.

We have tried inserting another cartridge and power cycling but the warning does not go away. 

I have done a cold reset on the printer. 

I have also updated to the latest firmware.

Any help would be greately appreciated.

[Apone]

i'm wondering if the issue might not stem from a defective drive motor.  remove the right side cover and then hook it back up to print.  see if there is movement from the motor & main drive assembly.