Found the mfr's website and instructions for gloss restoration, which I have reproduced below for the next frustrated owner who's looking for help
"¢ Mild detergent
"¢ Soft cotton cloth
"¢ Turtle Wax® Rubbing Compound Heavy Duty Cleaner
"¢ Turtle Wax® Polishing Compound (for buffer use only)
"¢ Mechanical buffer (optional)
"¢ Turtle Wax® Super Hard Shell Car Wax Paste
1. Wash the Crane Composites RV panel with a mild detergent and water.
2. Dry the Crane Composites RV panel with a clean, soft cotton cloth.
3. Apply heavy duty cleaner by following the directions on the container.
(If a buffer is available, substitute polishing compound for heavy duty cleaner and buff polishing compound lightly).
4. Wash the Crane Composites RV panel with water and dry the surface.
5. Apply car wax paste per directions.
I did this with my buffer and was quite pleased with the shiny results. Old school Turtle Wax white polishing compounding in the tub worked great.
My siding was made by Noble in 2003, but they were bought by Crane Composites in 2006. The link to above info can be found here: