Re-moving anodising

Not necessarily correct subject line.
I have Aluminium parts, which I previously had polished and then anodized. Been in saltwater use for 3 years and anodizing performing very well.
However due to mechanical damage on one part (aprox 40" x 4" x 3/4") , need to get it re-anodised.
Now if I understand things correctly, you can't put anodising on top of existing anodised finish - you have to remove it.
There is an option to remove using Caustic Soda solution, has anybody done this ....? if so what strength do I mix solution, how easy does it come off ?
Plan B ... is to polish it off ... I don't have wheels or rouge to do this, so would have to pay anodisers .... they were honest when i first had job done, that most of cost was time spent polishing parts ready for anodising.
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