tuner spots on the drum of 2035

[akbareshghi]

My blade and charge roller is new and rebuild pcu and all things work well (high quality copies) but after many copies (higher than 50 copies but varied between rebuild and clean pcu) these toner spom appeared on the copies .
Please help me exact cauae of this problem?
Toner drop from Front Entrance Seal - Toner Supply In The upper pcu assembly to drum surface and excatly appeared on the copies .
I changed new blades and charge roller and clean bushings of charge roller but after many times this problem recreated.
Thank you
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[rsyarcia]

how's the developer have you replaced it?clean the pcu properly use vacuum.

[CT Copier Repair]

Developer
front seal