Colour fall-off and imbalance in LBP5000 laser

I have a Canon LBP5000 4-colour laser printer for private use.

Can I control the output of the individual toner assemblies? It is a bit high on magenta in the blue (looks purplish) and yet the red is slightly orange-y - maybe the yellow is over represented too!

Also and more worryingly, the magenta toner is under represented on right side of a sheet where the reds are yellowy-orange and the magentas are pinkish, getting darker over the first 60 cm of the sheet. I replaced the cart, rocked and shook it as is usual but the fading is still evident, if a little less. Can anything be done to the printer to even the flow of toner across the page, please?