streaky printing?

I guess it's time to re-tell the story of the toner and the toilet.... I was halping a friend fix his laserprinter (Canon SX engine, if it matters), and we took the toner cartridge apart for some reason or other. One part of said cartridge collects the waste toner, and we decided to empty that out [1]. Undoing a couple of screws released the top of that container, and said friend decided to dump the contents into the toilet. At this point we discovered that toner floats on water, and it would not flush away. FOrtunately one of us though to add some washing-up liguid (or other detergent), which got the 2 to mix. It also produced the most amazing black foam which did eventually flush away.... [1] I wonder if the waster toner container being too full could be the cause of the original problem (streaky printing). Practical experience has shown that in some small phootcopiers you get streaky printing after so many thousand pages and you're supposed to replace the drum unit. Emptying out the waste toner will clear up the problem (and the drum unit will last at least 4 such emptyings, a significant cost saving...) -tony