Ricoh MP C4502 Poor Color Quality on Thicker Paper

[MO]

We have had a MP C4502 for several years and it has always had great color quality on regular paper or thick card stock. However, over the past few months the color on thicker paper has decreased greatly. I've reprinted things on the exact same paper and setting and they look drastically different today than they did only months ago.

The tech came out a few time and cleaned it and replaced fusions and such. I brought the issue up to him and he said it has to do with the thickness settings. Which I completely understand, but I've tried many different setting and the print quality is just so much worse than it use to be and worse even compared to printing on plain copy paper.

Is this just due to the age of the machine? Or is there some setting I can change on the machine itself?

I'm quite baffled how the same machine could change so much in such a sort period of time.

Any guidance would be very helpful.