I think you transposed Q802 for Q801.
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My theory is that the original problem was failure of R806, which caused R808 to overheat and change value, which caused the high voltage that lead to the shutdown issue.
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I did literally hundreds of these back then. The sequence was most likely that Q801 STR regulator shorted causing excessive B+ which tripped the shutdown. It also opened R806. Since the regulator was shorted, the open R806 had no effect on anything at that time.
At that point, you have essentially a jumper wire from the B+ filter to the flyback. So instead of having a regulated 125v, you had 160V feeding the flyback.
Once you put in the new STR regulator with the open R806, the short between the B+ and flyback was gone, the regulator was now out of the circuit, and the 20W R808 now had to supply what B+ it could.
That is a series/pass circuit, and the purpose of the 20W resistor is to carry some of the load for the STR to ensure it's reliablilty. By itself (like when the STR is either removed or dead), the 20W resistor can't supply enough current and it overheats.
With a working STR circuit, the STR then carries the rest of the load and tightly regulates it. With the replaced 47 ohm resistor allowing the STR to do its job (carrying about 70 percent of the load and regulating it), the resistor runs cooler.
John