mercury 2.4 v6 temp senders
 

hi i was wondering if anyone can tell me the difference between the temperature senders on a mercury 2.4 v6.looking from the head end the one on the right works,ie the gauge moves up when its imursed in boiling water,but the one on the left doesnt,it is also different in design,my warning buzzer is constantly on even when engine is cold and not running,could this sender be faulty and sending a wrong signal to the buzzer??

thanks,jamie