Obviosly given the lack of succes I do see how its not something we can put together in the back yard but among all the idea this one looked to me at
the time(and still doeS)as the possible one.
Yes ofcourse there is friction but who knows one day there may be 'super lubircants'(like superconducters).
OTOH none of these are actually any more of a PMM than a motor ttached to a solar panel