that's great news. Would you be able to measure the voltage on the electrolytic caps, C845, C841 and C369?
And if not too much trouble the input and output of the VR, IC318?
If you were to guess or try to narrow it down to which resistors may have had the poor solder joint--the little one between pin 4 and 5 of IC318? the little one by C844 near IC702? Did you happen to get a picture of the area around IC702 after you pulled the waffle plate?
here are some notes from previous posts, not sure if they would have helped find this issue or not, but will repeat them for future troubleshooting:
There is a 330 Ohm resistor from pin 4 of ic702 to the gate of TR301. It has test point solder blobs on each end that you might be able to reach. Maybe it is open circuit?
IC702 (on bottom side) provides the gate drive for the FET, so it is likely not doing it's job. And IC318 (on upper side) provides the feedback signal to ic702, so it will be one or the other of those two chips, or some little passive component in those circuits, resistor, cap, diode, etc.
or bad solder joint of a passive