Deck marks

I've got several small marks on my deck that look like they might be bits of rust from old fittings, and I cant seem to get rid of them, I've use something called a 3G Compound, no idea what its for, but it doesn't seem to work.
Has anyone got any advice on the best way to get rid of these marks?

Try using Bar Keepers Friend... works wonders, super cheap and typically available at most US super markets. Comes in a goldest yellow can that look like Comet or Ajax.

http://www.barkeepersfriend.com/

I found that ajax or comet or any of those cheap powder cleansers work great at getting everything cleaned off with the least effort. Then I re-polish if I want the original sheen back. A complete scrub once in a while keeps the decks looking good.

How do you Re-Polish ?

Boat polish either by hand or electric buffer/polisher.