I have just acquired a 1993 Nissan NS40C. Looks beautiful. Clean. Starts with one turn of the key (electric start) and sounds great. When it runs on the muffs there is no water coming from the telltale. The impeller looks fairly new, gaskets good. There is no visible water at the thermostat either. I am new to boats. Should I be concerned about there being no water from the telltale while it's on muffs? The previous owner said it was a beast on the water. I pushed a cleaning brush up into the telltale hole and got some gunk out but not much. Don't want to blow motor. What would be my next step? Should I take it to the lake and see how it does. New nervous owner. Any help is appreciated.