C-450i Drum Wear, on multiple machines

[Oystercopy]

I have noticed a trend on this model of the drums wearing excessively on each end. One machine was so bad, it ate through all four of the front of the drums, but you can also see the wear happening on a machine I have in shop, in the same fashion, and this machine only has 90K on it. I have attached pics of both the drum wear and also the Xfer Belt, in that same machine with 90K on it. Something is obviously going on with these things, as I've never had a machine (color Bizhub) wear drums this way. In fact, I'm able to get much more life than the OEM states out of most drums, but not if they're tearing through the coating and into the substrate.

It almost seems as if there is undue belt pressure on the ends of the drums... Or, somehow, the developer units are causing this excessive wear.. maybe the doctor blade gaps on this model are off and they're too open. No idea.

Any help appreciated!
OC

[Larhal]

Have you disassembled a drum unit to see if the cleaning blade is the cause. Looks like that to me especially on the yellow drum unit.

[tsbservice]

Try to remove only belt from ITB and inspect rollers under line for heavy toner deposit.
There were also bad batch of drum units where charge rollers containing the surface additive may damage drum body.

[copyman]

Are they aftermarket drums, blades, etc?

[Albonline]

Try to remove only belt from ITB and inspect rollers under line for heavy toner deposit.
There were also bad batch of drum units where charge rollers containing the surface additive may damage drum body.

looks like the edge of the xfer belt , are the prints reduced or otherwise distorted?

[scanmc]

You mention that the same model units are having this issue. I do recall that one of the FW versions had something that addressed premature wear on the drum units. Not sure that this issue is related to that but who knows since it's happening on other machines. Just my two cents

[Oystercopy]

Thanks for all the responses folks. I usually have the machines all at the highest base level FW, but wasn't aware there might have been a special FW for drum wear. Yes, this is happening on muitiple machines, all C-450i's for some reason. Don't seem to be having this on the C-360i's that I'm aware. I was thinking something might be going on with the transfer belt pressure also, since belts seem to be wearing in that same spot. Will do some checking.
OC

[Oystercopy]

Have you disassembled a drum unit to see if the cleaning blade is the cause. Looks like that to me especially on the yellow drum unit.

Actually, that really damaged Yellow drum is from a different machine than the one that I showed all the other drums pulled out. That machine had ALL FOUR drums damaged that way, the same way the yellow one was.
OC

[Oystercopy]

I looked into what Scanme said and there was some kind of mention of drum wear in a bulletin back in year 2020 (but I never could find that bulletin)... It was referencing having G00-B5 level FW loaded. We're way past that, and I assume all levels of FW include the previous fixes, especially as far back as "B"..? The idea that doctor blades are off would have to apply to a whole series of machines, but I never found anything in any of the bulletins about that, particularly. Of course, like TSB said, these could have just been a bad batch of drums and we're past that now. But were I not able to convert the black to the color drums, this could get REAL expensive, replacing all the color drums... This particular machine in my shop is at level H on the F/W, so it should have been past B long ago....