Fixed VVR issue. Bad FET?

[soma_hero]

So i rigged up a VVR for a fixed bias submini amp i'm building. B+ about 140V. I'm using an ST P16NK60Z for the B+ and an NTE 2373 for bias.

http://st.com/stonline/products/literature/ds/10249.pdf

So on the drain i've got 140V, so also 140V on lug 1 of the pot. On the middle lug of the pot, the voltage will vary with the turn of the pot, down to 70V (I need to change the resistor to allow lower voltage.) So far so good.

Now, the gate and source of the FET don't change with the turn of the pot. Solid 140V. Since I"m getting voltage I would imagine the FET isn't fried but since the pot forms the voltage divider and the FET limits current, I could have a fried FET and still get voltage through the pot?

Think my FET is fried?

Bias section of the VVR works fine, no problems.