Canon IAR4245 Dark Lines/background

[Rod...]

Hi all, thanks in advance.
Here are samples of what it's doing. We had a tech out here for this actual symptom of dark copies/prints (appears to have dark laser lines?) and he noticed the fixing assy had some sheets wrapped around upper fix film assy and the coating was worn to the metal of the film. Naturally replace the assy (and the drum for good measure it was also hi in yield). The symptom did not change. I showed up and played around with the HV-PRI and finally got the quality of the copies to look good, both "OFST1-DC/AC" were set to (+10). This brought my HVT-STS>PRIMARY to 1602 (from 1365, written on sample1). Customer called back today and said the print outs are starting to get dark again, not as bad, but noticeable. I was thinking about adjusting Primary again, any Ideas?
We did put aftermarket drums in before, but have since used OEM.

[Rod...]

*Crickets

I went back and did a DC con clear to no avail. After reinserting values from the P-Print, I adjust dev bias down to -35 (from 0), that seemed to give me a very good/clear image. My dilemma is the service manual says to replace several things, and I'm trying to keep from throwing parts at this machine.

...thoughts?