OKI C531dn colour laser

[argee45]

I've had the above printer for a year or two and it's worked faultlessly until macOS Mojave. Now, certain web graphics print as pixellated blocks, but exporting the page as a .pdf allows the file to print correctly. I suspect that the problem lies with the lack of Mojave driver, as everything prints correctly on my other inkjets. Anyone encounter similar problems, or know of a solution, as OKI are no help whatsoever?