"I'm looking at a 1998 25hp Mariner, serial #OG640194. I am not at all familiar with this set up. How do you increase RPM for start/warm up without putting it in gear? The owner tells me that he works at the Mercury plant here in Wisconsin and that "the guys at work went through the motor and all is well". Does this sound plauseable and if so, what would this motor be worth (ball park)? Thanks for the help."