Problem in C452 black color solid

[myster]

I have a C452 copier that does not give a solid black tone. In the test you can see how it prints as zebraized (IIII).
I have changed transfer belt, transfer roller and drum to black. The black developer is "new". Any ideas?
Thank you5264052641

[Drivee]

Look to me that toner is damaged by heat. One of possibilities... Also, try to print that page in CMYK where all 4 colors will be mixed. I have pdf so PM me and I will send to you. Or simple just download Lombardy low test.