I have a 1961 crestliner falcon..14 feet with a 1970 40 hp evinrude.It was in the boat house for 30 or so years....The original speedometer front plastic cover was filthy so i cleaned it up...Do you think i could replace the plastic with a glass one...Either way it dosnt seem to work. What is the basic concept in hooking a vintage or new one up....there is some type of hook at the transome and a dirty old hose attached.