You probably could
Doesn't look that hard to turn an HF6 into a WF6, as long as you have a 3d printer... I doubt you could find any parts for this machine anywhere, outside of maybe a thrift store in Europe, or calling Lindhaus directly. I think older HF6's had the same pre motor filter setup, (minus the float valve) so that could probably be done too. Not that anyone ever would, but, it'd be cool to take a junked out HF6 and see if anyone could.
Thanks for the brochure and old archive page! Had no idea you could find those!