I've got a canon i250 which is hardly used but recently I bought some black cartridges for it. They were cheap but it said they were compatible. I printed a one page document which printed perfectly. A few days later I tried to print a longer document and it came out with smudges in various places. I've just heard that if you load too much paper it can cause this. I had put more paper in than usual. I left it overnight thinking that resting the printer would solve it, but it's still the same. Can anyone help? Thanks.