Part 2:

IF, IF, IF you do this, you take ALL responsibility and ALL risk, but.. you can disassemble the controller, locate the stop tab, and bend it so that it no longer stops at 400, but goes past that. You NEVER want to go more than 500 degrees, and you will have to guesstimate that.

I put a scribe mark on mine, and I start out by setting the griddle to the max (400) letting the motherboard temp stabilize at the max it will reach at that setting, and then take the temp up another 50 degrees (compare the scale and turn the knob up the same amount). I let it stabilize there, and then if I have not reached the desired temp, take the knob up another 50 degrees.

IF you cannot reach 150 -170 with the griddle modified, then I would not try to go any further. You also have to keep in mind that without the stop, you CANNOT go past the low position when you turn the controller off, or the screw will come out of the contacts (continued, Part 3)