My dear you change development unit
Part number is: B237 4053 (North America)
B237 4054 (Europe)
I Expect this will be very expensive as it is not designed to be replaced as an entire assembly, but rather repaired as needed.
Are you a tech? I suspect not. You need to remove the drum unit, disassemble, separate the drum from the development unit. Remove cover of developer unit, add developer, reassemble, and run SP2214 to calibrate.
This is NOT a procedure to be performed by an end user...no disrespect intended.
make sure there is no paper at the back of the tray.also make sure the tray lift motor is working.the last thing to check is that there is nothig broking of the back of your paper tray..
remove all paper from the trays then turn machine off wait a few second then turn back on should reset then reload paper
sc 302 - charge roller current leak. strip the drum unit (dmu) and clean the unit