Copy of konica 7135 is unclear while running. at first is copy is clear, later the copy is not clear... blurred

it always cause sparks to charging unit and Horizontal lines produce.

1 look to the drum surface for scratch if their is replaced it. 2 the write unit might already defective. Damage drum will cause sparks to charging unit and Horizontal lines produce.

Go to Touch Panel adjustment you will see "+" to the 4 corner of the touch panel use pointed object point it MILD on the center of the 4 "+" . Off / On

When C-35**,C-38** or C-39**(fusing temperature related
abnormality) occurs, be sure to repair defective parts before
setting DIPSW3-1 to 0. Setting DIPSW3-1 to 0 with defective
parts not repaired results in a fire.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/normanj_7893313f0751935f

F 28-01 High voltage power supply abnormality.
Ihe charging ON/OFF operation has been performed five consecutive times since the charging trouble detection signal was detected at start of charging.If there is a paper in copying process when this jam occurs,the machine stops after completion of copied paper ejection.Verify the charge wire,change and the holders.Check the high voltage unit.
F - 28 -02 Toner transfer wire malfunction
F - 28 -03 Toner separation wire.malfunction

take it back to the store where u bought it and report the problem

yes, u have 3 clean comb electrode, scorotron grid and corona channel of corona unit....

I have never heard of a developer moving backwards!!!!!!!!!!!!!!!!???
the motor that runs it, the .... there is too much involved to mention. A developper moving backwards will spill so much toner in the machine anyway.
If you get a copy and then it goes blank, that tells me you have a problem with the SEPERATION UNIT, it may be shorting out causing the paper to rise against the drum giving you blank copies.
A blurr copy tells me there is a problem with the Scanner/Optics area. maybe the rails that the scanner run on are too dry or has a problem, the optics(mirrors) may be misaligned.
Not sure what you mean by (hanging) ??

The 1015 / 1120 were prone to the lens drive gear cracking, and not holding to the shaft.

Sometimes you will get a lens initializing error, sometimes you wont.

But this is most likely the problem.

Please be more specific in the problem:

Are they crooked on the glass, or through the RADF?