Got a bf 50/just serviced,1 year old,done 60 hours,oniy reving to 3 thou/no the plug in comp,says its the HO2 sensor,done the unplug and resart trick,ok in a tub of water going to 6thou revs but going out to sea in good weather only revin to 3.5 thou,they say the sensor is us,but what if the...