Discovered what the original problem was.
A rectangular tunnel between the colour wheel and the first lens, going
across the airpath of a fan. Made of silvered microscope slide glass , 4
pieces forming a rectangular tunnel about 6 x 8mm but the glue at the
corners failed with time or heat and the retaining spring pushes one edge in
a bit.
Removing the spring and the tunnel collapsed, i'm surprised the fan air
didn't totally disloge them.


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