Veteran digital printer, printer forum noob

So I searched the forums here as well as some other sites to gain some insight into our dilemma, which has to do with a brand new 8000vp (b4000 server). We were running a 7000vp with retrofittings for a 7011vp for years and we finally decided, after 11 million impressions (mainly 12x18), that it was now time to move on. Here's the problem (which actually occurred on our old 7000 from time to time) -

Calibrate, run a sample of a booklet or postcard, sample looks good. So go ahead and run the job right? Obviously, who wouldn't? Well, say the run is 500 of a 3 page document, about 100 sets into the production the colors start to shift toward magenta. At first it's subtle, and worsens as you progress. Then stop the run and recalibrate...looks good, start production....stop when the color shifts, recalibrate, rinse and repeat.

Any ideas or help is greatly appreciated.

 

I now understand why there are no reply's to this query. Canon can't even localize the problem, had multiple specialists work the issue over the past few days. Looks like we may have a lemon, good thing it's only 3 months old.

 

Ive had similar issues. The machine love to go heavy on magenta for some reason. In the settings menu on the machine you can reduce the magenta saturation. I was able to get a few long runs completed this way. your prints will initially look a little cold, but once the machine starts to lay on the magenta you'll reach an equilibrium. kind of a "band-aid" type fix. I know.

In the service settings you can permanently reduce the transfer voltage (or transfer current) of magenta a few points. This is another option.

 

UPDATE: Canon specialists were able to locate 2 other units on the East Coast with identical issues. As it turns out, someone didn't do their job on the assembly line at the factory. There are default target values that are manually entered into the unit somewhere in the manufacturing process and they were all left at 000's, so the printer is constantly trying to hit certain shading targets without numbered values...a perpetual internal fight over numbers. So far so good, waiting for a substantial print run to see just how stable it is now.