According to Mark, it appears that your statement regarding the readings being correct are correct.
I was freaking out seeing house bank voltages (24 V+) between the POSITIVE side and BONDING side, but according to Mark, this is indeed what we should see.
I verified that my Masse Test Light is indeed working, as Mark suggested, by jumping POSITIVE to BONDING then NEGATIVE to BONDING and seeing if the respective light illuminates - they did.
As Mark explained it, seeing voltage only indicates potential for current flow.
Hence, it appears we don’t currently have a leak - no measurable current flow. I’m going to change the zincs and keep a close eye on the new ones.
Thank you Bill H, Bill R, John, and Mark for your help. In the end, it turns out I didn’t have a problem in the first place, but you all helped me reach that conclusion, and learn a good deal in the process.
All the best,
SM #466 - s/v Rita Kathryn
Currently Exploring City Island, NY