I wouldn't do a bunch of hard head cleanings. It looks to me like a head alignment issue or possibly feed compensation, you need to post some test prints in addition to what you put up. Even with the printer plugged in when stored, you should run off a print every now and then. Either way, it is a process so be methodical rather than throw stuff at it. If it is anything like the older Rolands, it is all laid out step by step with pictures in the service manual.
I don't think that the material or profile would give you consistent banding either, but don't know for sure