I've used Citristrip on a couple of rods and it didn't damage the fiberglass.

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Use some other search terms as well to see various refinish methods. Citrus strip is relatively mild, but still may be more aggressive than needed. In many cases, unless there is blistering, blotchy discoloration, or other obvious visible damage, there is little to gain in stripping all finish. Sometimes what doesn't come off easily doesn't need to come off, and a little careful scraping or buffing will tell you that it is one there for good. A sprayed or finger-rubbed self-leveling finish may be all that is needed after a thorough buffing.