Dell S2825cdn CTD Sensor Error 009-340

Hello,

One of our printers started showing this error today. I have read a lot on how you just need to clean the sensor to clear the error, but I haven't seen anything on this specific model's sensor location. I believe I found the sensor but when I tried wiping it with a cotton swap there appeared to be no residue that came off it which leads me to believe I am trying to clean the wrong item. If you are able to provide a more detailed account of where the sensor is for this exact model or of another possible solution to this error I would appreciate it.

Thank you.