Rp 3700 / ink overflow / ink not distributed properly

[szupsolog]

Hi all riso fans and technicians
So far it's been an abundance of knowledge here regarding riso, thank you all!!!

We are group of artists playing with used RISO Rp 3700 for a year, it s been running once a while since then without major problems.
Recently, we encountered a problem with red DRUM. The ink was not distributed on half of the screen (confidential master on the photo attached)
and after few copies overflow ink error appeared (t04-513) which makes impossible to make any print.
The following day we tried to run it again and it did with the same result as the day before; ink not distributed properly and after few copies error ink overflow appeared.
We tried cleaning the screen with fair amount of alcohol, nothing changed.
Screen Shot 2020-11-24 at 13.17.22.jpg
Do you have any ideas what may cause the issue?
Or any tips for fixing?

Greetings, Bart

[20gaugeO/U]

For whatever reason Red or anything else in the red spectrum likes to Ink Overflow the most.

You need to open up the drum shell and clean out all the crappy old ink from the ink bead. Take a small paper clip and unplug the ink dispersion nosals that drop the ink out. Clean off the ink detect and overflow antenna sensors above the bead. Probably need to get a new tube of ink if that one is older than 2 years. May need to clean the drum and screens if the ink wasn't making it to the master on the drum before this happened. Put it all back together and test it.

OR throw the Red Drum away and call it good