How can I fix my Thermostat control for Westinghouse model KB251RDM2 ?

It was not working at all, the red on light and the coil did not light.

I took it apart and found a wire that had burned off at the connection to the thermostat. I fixed that and noted that the post that that black wire connected to was loose.

I put everything back together and the red light and the coil now work.

The problem now is that the thermostat turns the coil off at about 300 degrees and takes a while to switch back on no matter what it is set for (we can set it for 500). That is according to our oven thermometer.

Any help would be appreciated.