Originally Posted by Artif
Yes, they have to be clean to be functional ...
I hate to disagree with Yandina < Yandina Marine Electronics
>; but, in this case, I will.
A Zinc Oxide (white rust) coating will isolate a zinc anode, rendering it totally ineffective.
Connect your ohmmeter between the Anode & Shaft, expecting to read continuity. High or infinite resistance confirms your visual diagnosis.
This is generally a bigger problem in fresh or brackish water
, but also occurs in salt water
Wire brushing, sanding
, or scraping the surface only provides a temporary solution, and the oxide will quickly reform.
I would replace the anode, rather than clean it.