the blcak line that runs from top to bottom is due to a dirty misaligned print head...do a full printer maintenance on your printer/scanner . Once the heads and rollers get clean and the printer is aligned, it should get rid of any black streaks or lines. I own a Brother Printer/scanner and it did the same thing to me, as soon as I ran maintenance on it..it fixed the black straks and lines I had on my prints.
Your unit requires replacement of its maintenance kit. You will not be able to do this by yourself unless your are a technician, which I assume you are not. The cost for this repair will not be cheap, you are going to be up for over $500 and you need to do it through a brother warranty service centre.
Lift the scanner cover and next to the scanner glass is smaller glass. Make sure there are not any pieces of paper, ink pen marks or dust on that glass. It will leave a black line while copying and scanning. You may need to get a flash light and shine it at different angles to see a pen or pencil mark on the glass.
The opc sensor is not sensing the belt. Open the front cover and remove all the toner trays. You will see the green OPC and the sensor is located in the left upper corner. Also open the top cover and remove the OPC. Clean the sensor with a soft bristle brush. Also make sure the OPC left side is free of toner deposits. This may incorrectly trigger the OPC position sensor. Hope this helps.
Well it's a low temp error for the fusing assembly. Sounds like you already had it in Maintenance Mode. Sometimes those errors can only be cleared out by entering maintenance mode and pressing 9,9 to exit out. Should then start the normal warm up procedure. If the problem continues then reseat the fuser or take it out and measure for continuity across the lamp and thermostat. The service manual also recommends checking the line voltage. Basically make sure it's plugged straight into a wall outlet and no other large power sources on the same circuit. Example, another copier or this time of the year a small space heater.
Maintenance Mode enterance Press Menu/Set and Black start button and Up arrow 4 times. Machine will read Maintenance on the display if done correctly. Press 9,9 to exit of the mode and the machine will attempt to restart normally.
It's not unusual for paper to hit the bottom of the print head, especially if the paper is bent. This can cause smearing. If you have pets, you can check for pet fur in the printer, or other foreign material inside that can also cause smearing.