I simply meant that heavy arms are often incompatible with lightweight tables. Being a VPI dealer I can see how heavy their arms are and as they are probably the most common unipivot arm I suspected someone had tried to mount one on a table that was too light. There is nothing about a unipivot arm that would prevent it working with any table that it was physically compatible with. I am probably one of the few left who used the Pickering unipivot arm, which was a steel spike resting in a plastic cup on the arm, seemed to work then. I had the Transcriptors fluid dampened arm, which was probably the first one of it's kind. As well as the one [audio & design?] which rested in a mercury bath, no wires as the mercury was suppose to conduct the signal. I was smart enough not to set the last two up as they were Rube Goldberg on steroids.