In a message dated 9/24/99 4:56:26 PM, ral@LCFLTD.COM writes:

<< Normal use causes the aluminum to loosen at all connections due to thermal
contractions and expansions at the joints. >>

Aluminum is one of those materials that "cold flows".  If anyone ever tinned
a stranded copper wire and put it under a screw terminal, they know about
loose connections and cold flow.  It WILL get loose, no matter what the
fixtures were designed for.