Also check your main power wiring for degradation. I started seeing some electrolysis on my prop (hull #447) about a month ago when cleaning the bottom (even though there was still some zinc left). Then two weeks later, the engine would not start. I tracked it down to the 1 gauge wire coming from my battery switch and the ground from the batteries to the engine being rotted more than half way through. I changed all 1 gauge wire in the boat a few days later.
I just pulled my prop yesterday to have it reconditioned (hopefully its not gone too far)
