Inboard running cold

[CHANCE1234]

Well i checked her out today, and my first step was the thermostat. I ran the engine for about 20 minutes before. then waited 5-10 minutes and removed the thermostat, and it was open. Which i believe means it was stuck open. I didn't have a new one so i tried to clean it and put it back in. Then started it and the gauge started to move after about 3 minutes. My gauge does not have numbers on it just marks, and it got to the first mark just above the "C" and stayed there for the next 20 minutes at idle. Is it even worth it to try to clean a thermostat or should i just get a new on. Wires and connections all looked good and tight. Hopefully i fixed it or will just need to get a new stat. Thanks for all the help again guys.