Much more mysterious failure mode , that yellow goo again?
Removed both FETs and they cold tested ok , changing conductance state, via
DVM "diode" test, so probably ok . There is that yellow goo in this area and
one resistor covered with it is 120K 1/3W dropper from the anode rail, so
difficult to check in situ as between 2 electros, sets the bias. Something
chemically has gone wrong with it. Small patch of body coating shows
perfectly normal cream and part of a red and brown band, again no thermal
discolouration. Under the R the board is perfectly normal green colour. But
the r is o/c , now replaced with 2x 240K 2/3W raised off the board , JIC a
heat problem but I doubt it. So as well as encouraging
deliquescence/hygroscopic or whatever the word is for taking moisture out of
the air and encouraging corrossion it looks as though high voltage has some
deliterious effect with the dreaded yellow peril.