Horizontal banding when using black ink

[meoww]

I have an EPSON Stylus CX3600 and for a little while now (since Christmas?), every time I try to use black ink only, horizontal banding is evident and so the printout is unusable. When I print in colour, things appear fine, but I don't want to print in colour all the time because the majority of my printouts are purely black and white. I have tried using different paper and changing the black ink cartridge, both to no avail. Previous to that, I have run numerous nozzle checks and print head alignments but neither of these have changed the situation. Does anyone have any suggestions as to how to fix this banding problem, as I really need the use of my printer quite regularly and it is getting very annoying! I do not use original EPSON ink cartridges, but I don't think this is the problem because I rarely use them and never usually get this problem.