Back in Oct of 2013 after I took possession of Mystic, I noticed the low Oil Pressure alarm did not work. After replacing the buzzer the problem persisted. I opened the panel and found the sensor lead from the engine disconnected. When I reconnected it the O/P alarm was weak sounding, like it wasn't getting enough voltage. I dove into the wiring and could find nothing wrong. Tech support from Westerbeke and Catalina could not help. It got to the point the poor gentleman from Westerbeke seemed flustered and could not provide anymore help. At that time I simply made the decision that a sick sounding O/P alarm was better than none at all. I accepted it and lived with it. Just recently ( and I honestly don't remember from where) I saw a service bulletin that stated if you have a Westerbeke W20B attached to a Catalina High Efficiency Instrument Panel (me) that you must disconnect the O/P warning light on the panel. The light is wired in parallel with the buzzer and apparently the added current draw of the light is enough to reduce voltage to the point the buzzer sounds sickly. I disconnected the light and the buzzer came back to its robust self. I have discovered there are many different engine and panel combinations on the 270. I am an electrical/electronics guy and this had me totally stumped. I don't know if there is anyone else out there with the same issue but this simple fix will take care of the problem.