Brand : Philips
Model: KB-9000

Hello all,
This toaster oven is about ten years old. It was not reaching
temperature so I replaced the mechanical thermostat with the proper
replacement part from Philips. The old thermostat had totally worn
away contacts. I figured this altered the travel of the bimetallic
strip. There is no adjustment for this.
The new thermostat chatters a lot. When the bimetallic strip heats up,
the contact doesn't make a clean break, and it doesn't do a clean
make. It also doesn't seem to be linear, either the oven is too cool,
or too hot. There is a lot of sparking in the thermostat.
What can be the problem? The heat path seems fine, there is a
probe-type assembly that holds the thermostat by the core and I
cleaned it.
Is there some sort of secret to getting these mechanical thermostats
to work properly?

Worst case, what toaster ovens do you technically-minded folk
recommend? There seems to be more and more fully electronic controlled
ovens out there, are they debugged? Which brands are good? I'm not
interested in mechanically controlled ovens anymore, I get the feeling
the quality is not there anymore.
Thanks in advance.