Have tried CLR 50:50 with water but was not that successful.
There's a product called Stain-Magic by Yoshimura but need to buy it online.
The youtube below shows by applying the cream to the header the discolouration/rust comes off easily (don't want to spend hours with wet sand paper etc).
I want to work on the headers this weekend.
What similar effective products to Stain-Magic would do the job that I can purchase at Bunnings?
Thanks