Everett key

[robert sadowski]

Dear List,
     What size Allen key fits the rounded screws on the back of the Everett
verticals 
that hold the top on?  I'm assuming it's metric.  I've tried two different
sizes of metric
to no avail.  Also, I found two different hardware stores with two
different sizes of 
6mm keys.  One has on it "metric #17" beside the 6mm.  Are there two
different
metric standards or am I missing something?

Thanks, 
Bob Sadowski RPT
Erie, PA.