Well I posted about some tach problems a day or two ago. I found a cruddy connection causing low voltage on the power wire, but it still did not work. Well over a couple Captain 'N Cokes (practicing for the Captain Morgan pose off ya know) my friend and I were tinkering with the boat in the backyard. He's an electronics tech and figured what the heck, let me pry the outer ring off and take this tach apart. Well the rubber grommet in back was not sealed at all, and there was a tiny and I mean tiny spider's web inside on some contacts....blew it out with air, tach works fine now!