High power combos that go intermittant
after a period of use.

If they use
an elbow jack on the amp to speaker link ,
replace with conventional, if poor manufacture.
Check the internal construction and if
poor mechanical connection at the elbow means
the shaft can turn , with pliers , when cold,
so a resistance and voltage drop, heating the plastic
disc that is all that forces a mechanical connection.
So progressively worsens, so when heated by the current,
in use, the shaft will turn with finger pressure only
rather than requiring pliers.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/