Atwood Water Heater DSI Fault

We have had this problem since we purchased the MH...about 2 years ago. We did purchase it used and our first trip out yielded the problem...previous owner said he never had the problem before (take that for what its worth). The circuit board is potted, so no real accessibility to the components, however, visual inspection does not indicate any obviously burnt components. I wasn't planning to replace the circuit board again...all indications suggest it is functioning properly (sending signal to light burner, shutting down when TSAT and/or ECO are manually disconnected, etc.). I am certainly leaning more towards some incoming power deflection or spike that is taking the ECO and TSAT out (but somehow not affecting the circuit board). I keep trying to find a common denominator when the items fail...i.e. connected to shore power, operating on generator or dry camping? And I really cant put my finger on any specific configuration that seems to be causing the failures. My next checks will include checking water heater incoming DC voltages (and probably ripple voltages) under different conditions (connecting/disconnecting shore power, connecting/disconnecting to generator, etc.) to see if the voltage spikes or varies to any obvious degree.