Hello Bill & All,
In Missouri we had a beekeeper try the vinegar machine with poor results.
Last I heard the used machine was for sale in a beekeeping newsletter. I
will add a few comments but must state I have NEVER used the machine.
The maker of the machine also produces a wax melter which myself and other
beekeepers have used with success. The maker of the machine is not a
beekeeper but a inventer. I have never met the inventer but have talked on
the phone to him on a couple of occasions. The idea behind the vinagar
machine does make sense to me and in *theory* the machine should work to a
degree. The Missouri beekeeper which used the machine said the machine
knocked down some varroa but the control fell far short of a 98% chemical
control so he discontinued the machines use on his 700 hives.  In my opinion
and buying a melter from the inventer I do not believe he ever intended to
*rip people off* but was trying to invent a non chemical cure for varroa.
Sadly like *ALL* non chemical controls so far they have fallen short of the
control *Apistan*(Fluvalinate) did when first released on the market. I
notice the vinegar machine is not advertised in the June issue of ABJ.
Perhaps if a beekeeper were to spend the time figuring out exactly why the
machine is not providing varroa control maybe the machine could be improved
to a point it could be used with success with other IPM methods. The melter
the inventer has made is very well made with stainless steel and galvanized
metal. They have held up for decades in commercial beekeeping use. I suspect
the quality of the vinegar machine is top notch. Many inventions  are
sitting on shelves because they didn't perform as intended. Sadly to say a
few of my own. I am writing this post from the outside looking in and have
no way of knowing the actual problems with the machine first hand. The
theory did seem reasonable to me.
Sincerely,
Bob Harrison