My newly acquired boat included an antique fathometer. The only ID on the unit is Datamarine. It's a round aluminum display with nixie tube readout. The rear panel has a "off/dim/brt" toggle switch, an RCA plug to the "glued to the hull" transducer, and a four terminal strip "gnd/+12v/alarm/alarm".If I power it up, it does nothing visible, except a single LED flashes in the transducer cable is removed, so it's at least got a pulse.Here are the questions:1) Anyone know a model number or have a manual they could scan and email?2) Anyone know if the transducer might work with later nmodels?As a confirmed tinkerer, engineer, and cheapskate, I'd really like to take a crack at fixing the thing. Unfortunately, my "shop" and my boat are 80 miles apart, so I either need to move all my test equipment or simulate a transducer. Any ideas?