Two R3131 self-test failures - First - CPU - easily fixed with new 3.6V RTC battery and reset button, with great info already in this forum. Second failure - I then have a self-test "total gain" failure. Same failure when cold and after 30 minute+ warm-up. From postings I have already found, suggested to replace R120 in output stage of RF board from 390 to 470 ohms. Other suggestion, to replace 4072 opamps (posting said two, but there are three on the IF board near output connector). Haven't started either of these - would like more confidence that either change makes sense. Thoughts? Thanks.