I have a force 120 (1201x90b) (020810) when I start her up she rev's at 4000 and then goes to 7000 in neutral. when in gear the tacho goes crazy. At full spead it doesn't register then when you back off it goes anticlockwise. <br />Is the unit broker<br />or is it wiring<br />if broke where do I get a replacment<br />will a car version work<br />thanks