What grit sand paper did you use? Normally I hit aluminum with an orange wheel and brown rouge then yellow with green and white with blue and had some pretty nice results. It's interesting to see how everyone does it a little different.
Did the whole thing in 600 once, certain spots several times depending how bad they were, then 800 on the whole bed once, certain spots that were really scratched or bad I sanded until they were smooth then started using the airways on them.