I have an HP 750C DesignJet which is a pretty horrible printer by modern standards but it is OK for some fun.
It was working fine. I stopped using it for a few months and now it is prints with noticeable banding. The odd thing is that if I print a block of a solid colour then there are no bands but if I print a photo there are. I have calibarated it and gone through all the steps in the manual without any success.
Is anyone familiar with this printer and/or suggest somewhere I might get some support (HP stopped supporting it a long time ago).