Hello, and thank you for choosing JA for your support needs. Happy to assist you with this issue.
When have you done the Maintenance procedures?
Have you cleaned the DRUM?
Have you cleaned the Corona Wire?
Now, a Fuser at 35% is ok, So I do not think it is the issue here.
The Corona Wire is used to Negatively Charge the Drum so the Paper can adhere to it as well as the Toner. This is before it is married to the paper via the Fuser, Sir or Madam.
Here is a guide for you Sir or Madam:
You have a multi-colored Laser Printer correct?
The instructions on the link above Also cover the OKI Printers also. Either the Corona Wire is on each of the Toner Cartridges or there is one the is removed and you use the cleaning device that is in the Printer for cleaning of the Wire.
You have Toner Carts in your model or Toner Bottles?
The video above shows the cleaning of an OKI Color Laser printer. Yes, the Corona Wires (Plural) also.
So, your Toner Carts do not have Corona Wires on them?
Also, I enumerated other culprits too. Did you consider the other options too?
Not a problem. Have a safe and happy evening.