Ok you've just established there isn't a short between pin 8 and ground. The difference in readings is because there's a semiconductor junction somewhere - like inside the chip itself - a good sign.
Can you identify the supply where the chip gets it's power from? If you can you should check that that is ok, and then everything in-between. It's possible you may be chasing a red herring if the power comes from the main supply, then this pfc circuit isn't your culprit. (I suppose that's another "leg" for your transformer idea).
I don't know enough about smp's or pfc to give any better help without more information.
It's my bedtime now, hope someone else can help meanwhile.