My water pressure gage has not worked since I bought the boat. The pointer was pointing straight down. Yesterday I decided to dig into it. I pulled the line line fitting off of the engine and blew into it - nothing. I then hooked the compressor to it, still nothing. I disconnected the gage and tried, still nothing. I ran a long aircraft drill into the tubing fitting from the engine end then tied the air compressor into it (in the cabin) and blew - the line cleared and I blew it dry. I connected the gage back and blew into it with the compressor - still nothing. But If I hook a vacuum pump to it the gage will register back-wards, but the tube and gage hold the vacuum so nothing is leaking. Looks like I need a new gage ? Where ?