Ricoh C3504ex intermittent light prints

[AEON]

I have a Ricoh C3504ex with very intermittent light prints. The prints come out almost completely blank, with very little text on the paper, see attached photo. It has been difficult to troubleshoot since it doesn't occur when I'm there. I believe it may happen for black only, but not entirely sure. I replaced the black drum and developer unit, transfer belt assembly, and black toner hopper and hopper motor. Help with this matter is greatly appreciated, thank you.

[slimslob]

It would appear you have posted the same problem twice!! In the future when you forget to attach an image, you have 24 hours in which you can click Edit.