The Dawson Kiln Sitter is simple: A piece of clay bends when exposed to heat, which releases a trigger that turns off the kiln. Once you know how the Kiln Sitter works, you will find it easier to adjust.
Inside the kiln, a small clay pyrometric cone is centered horizontally on the Kiln Sitter cone supports. A lightweight rod that pivots up and down inside a tube rests on top of the cone.
A metal block is mounted to the other end of the rod outside the kiln. The block is called a claw and presses down over the end of a hinged weight. The claw prevents the vertical weight from dropping. If you removed the cone and lifted the rod up, the weight would drop.
The kiln heats up. When the pyrometric cone has been exposed to the amount of heat rated for that particular cone, the cone bends, and the rod that rests on top of it moves downward. As the end of the rod moves downward, the opposite end moves upward. This releases the weight.
When the weight drops, it moves a locking slide, which in turns releases spring-loaded electric contacts. The kiln shuts off.