In my last attempt I used a regular 5R6 shunt resistor (not knowing that it needs to be fusible)
I blew the resistor, chip (new replacement) and transformer primary (which was 15R)
So I don't know what is left in the primary that could be at fault.
Could a failure in the low voltage section cause such a catastrophic failure?
The output windings on the transformer measure in the 0R2 range, but this would be typical I would think.
Measuring with the transformer removed, on the low voltage side I get readings in the Megohms or open, so no short there.