Where is the serial number on a kyocera copier KM3035

Question edited for clarity.

Error Codes > Kyocera > KM3035 > Code C6050 - PrintCopy ...

https://printcopy.info > model=KM3035 > code=C6050
Kyocera KM3035 · Code: C6050 · Description: Abnormally low fixing unit thermistor temperature • When only fixing heater M is on, fixing thermistor 2 detects ..

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On the left sde of the control panel when you'r facecing the copier their is a half moon knob rotate it to adjust the color/brightness of display.

chk first drum unit if it good condition may be toner defctive /clean charger

This problem can be caused by many reasons :-
1) Drum unit malfunctioning.
2) Developer unit malfunctioning.
3) Drum unit not getting proper electrical contacts located on the backside of the machine.

Total equipment cleaning and replace the main charge wire

What error message do you get? We've discovered that if firewall is turned on on the computer it can't find the computer. If you turn off the firewall, it finds the computer.

for a km3035 the add on IS
PRINT SYSTEM U PART #083H9503
FAX SYSTEM J PART # 023DB603

 Sounds like print card maybe bad.

I assume the print driver is on the server and shared. I would start there. I would think someone changed the default setting on that driver. Go to printing preferences, job tab, and see how it is set.
Or re-install the print driver and start over.
Of course, on any problem, Kyocera will always ask you if you have the latest software installed on the machine.