Cleaning X7 Alloy Prop-gctid401327

If this doesn't remove it start sanding. http://www.flitz-polish.com/index.ph...externalId=541

I have been offered an Mercury X7 Alloy prop. It is described as being dis-coloured after being stored for a while. It had last been used in salt water just after being cleaned down with Autosol Sovol polish (http://compare.ebay.co.uk/like/30054...bar&adtype=pla) I have not seen it yet to see the problem.

Has anyone managed to clean one back to showroom?